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140-699: The Battle of the Beams was a period early in the Second World War when bombers of the German Air Force ( Luftwaffe ) used a number of increasingly accurate systems of radio navigation for night bombing in the United Kingdom . British scientific intelligence at the Air Ministry fought back with a variety of their own increasingly effective means, involving jamming and deception signals . The period ended when

280-637: A Neutrality Pact in April 1941, and Japan adopted the doctrine of Nanshin-ron , promoted by the Navy, which took its focus southward and eventually led to war with the United States and the Western Allies. In Europe, Germany and Italy were becoming more aggressive. In March 1938, Germany annexed Austria , again provoking little response from other European powers. Encouraged, Hitler began pressing German claims on

420-564: A cautious French probe into the Saarland . The Western Allies also began a naval blockade of Germany , which aimed to damage the country's economy and war effort. Germany responded by ordering U-boat warfare against Allied merchant and warships, which would later escalate into the Battle of the Atlantic . On 8 September, German troops reached the suburbs of Warsaw . The Polish counter-offensive to

560-495: A bombing direction system based on the Lorenz concept through the 1930s, as it made night navigation relatively easy by simply listening for signals on a radio set, and the necessary radios were already being installed on many aircraft. For bombing use, the modifications to Lorenz were fairly minor. Much larger antennas were needed to provide the required accuracy. This was achieved by using aerials with many more elements, but it retained

700-625: A congested area (town, settlement, etc.) it must fly high enough so that in the case of an engine failure, it is able to land clear safely AND it must not fly less than 300 m (1000 ft) above the highest fixed object within 600 m of the aircraft. Member states are allowed to modify the low flying rule to suit their jurisdiction, for instance in the UK, the "500 ft Rule" allows pilots to fly below 500 ft as long as they are no closer than 500 ft to any person, vessel, vehicle, building or structure. The rules for flying near congested areas are

840-470: A flight may only operate under IFR. IFR operations have specific training requirements and certification required of the pilot, and increased equipment requirements for the aircraft. Additionally, an IFR flight plan must usually be filed in advance. For efficiency of operations, some ATC operations will routinely provide "pop-up" IFR clearances for aircraft operating VFR, but that are arriving at an airport that does not meet VMC requirements. For example, in

980-497: A much more accurate version of the same basic concept, which was eventually delivered as X-Gerät (X-Apparatus). X-Gerät used a series of beams to locate the target, each beam named after a river. The main beam, Weser , was similar in concept to the one used in Knickebein but operated at a much higher frequency. Due to the nature of radio propagation, this allowed its two beams to be pointed much more accurately than Knickebein from

1120-409: A new instrument was being used that automatically decoded the dots and dashes and moved a pointer on a display in the cockpit in front of the pilot. This device was fitted with a very sharp filter which was sensitive only at 2,000 Hz, and not to the early British 1,500 Hz counter-signals. While the jammers were modified accordingly, this came too late for the raid on Coventry on 14 November; but

1260-474: A one-eyed god, and might refer to a single-beam navigation system. Jones agreed, and knew that a system with one beam would have to include a distance-measurement system. He concluded that it might work on the basis described by the anti-Nazi German mathematician and physicist Hans Mayer , who while visiting Norway had provided a large amount of information in what is now known as the Oslo Report . Y-Gerät used

1400-557: A pilot to be able to see outside the cockpit to control the aircraft's altitude, navigate, and avoid obstacles and other aircraft. Governing agencies establish specific requirements for VFR flight, including minimum visibility, and distance from clouds, to ensure that aircraft operating under VFR are visible from enough distance to ensure safety. Under visual meteorological conditions , the minimum visual range, distance from clouds, or cloud clearance requirements to be maintained above ground vary by jurisdiction, and may also vary according to

1540-514: A pretext to initiate the invasion. The first German attack of the war came against the Polish defences at Westerplatte . The United Kingdom responded with an ultimatum for Germany to cease military operations, and on 3 September, after the ultimatum was ignored, Britain and France declared war on Germany. During the Phoney War period, the alliance provided no direct military support to Poland, outside of

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1680-765: A pretext to worsen relations. On 29 August, Hitler demanded that a Polish plenipotentiary immediately travel to Berlin to negotiate the handover of Danzig , and to allow a plebiscite in the Polish Corridor in which the German minority would vote on secession. The Poles refused to comply with the German demands, and on the night of 30–31 August in a confrontational meeting with the British ambassador Nevile Henderson , Ribbentrop declared that Germany considered its claims rejected. On 1 September 1939, Germany invaded Poland after having staged several false flag border incidents as

1820-469: A secret protocol that defined German and Soviet "spheres of influence" (western Poland and Lithuania for Germany; eastern Poland , Finland, Estonia , Latvia and Bessarabia for the Soviet Union), and raised the question of continuing Polish independence. The pact neutralised the possibility of Soviet opposition to a campaign against Poland and assured that Germany would not have to face the prospect of

1960-404: A series of three very narrow single beams, Rhine , Oder and Elbe . They were carefully aimed to define a precise bomb release trajectory. First a bomb release point along Weser was determined, by calculating the range or distance the bombs would travel between release and impact, and picking a point at that range to target. The Elbe beam intersected Weser 5 kilometres (3.1 mi) before

2100-743: A similar pact and rejected ceding part of its territory to the Soviet Union. The Soviet Union invaded Finland in November 1939, and was subsequently expelled from the League of Nations for this crime of aggression. Despite overwhelming numerical superiority, Soviet military success during the Winter War was modest, and the Finno-Soviet war ended in March 1940 with some Finnish concessions of territory . In June 1940,

2240-582: A similarly sized antenna; the equi-signal area was only about 100 yards (91 m) wide at a distance of 200 miles (320 km) from the antenna. The beams were so narrow that bombers could not find them without help, so a low-power wide-beam version of Knickebein was set up at the same station to act as a guide. The main Weser antenna was set up just to the west of Cherbourg in France. The "cross" signal in X-Gerät used

2380-401: A single narrow beam pointed over the target, similar to earlier beam systems, transmitting a modulated radio signal. The system used a transponder ( FuG 28a ) that received the signal from the beam and immediately re-transmitted it to the ground station. The ground station listened for the return signal and compared the phase of its modulation to the transmitted signal, which accurately determined

2520-430: A small cloud forming over the airport at less than 1000 feet technically requires the airport to allow only IFR flights using instrument approaches/departures. A VFR flight intending to land there would normally be denied clearance, and would either have to divert to another field with VMC, or declare an emergency and override the denial of clearance, which can prompt an inquiry and possibly result in adverse consequences for

2660-651: A straight line with a relatively high degree of accuracy, so much so that pilots could then find the runway visually except in the worst conditions. During the early 1930s, the concept of a night bombing strategic campaign began to become paramount in military aviation circles. This was due to the ever-increasing performance of bombers , which were beginning to have the capability to strike across Europe with useful bomb loads. These aircraft were slow and lumbering, easy prey for interceptors , but this threat could be essentially eliminated by flying at night. A bomber, painted black, could be spotted only at very short ranges. As

2800-519: A two-front war, as it had in World War   I. Immediately afterwards, Hitler ordered the attack to proceed on 26 August, but upon hearing that the United Kingdom had concluded a formal mutual assistance pact with Poland and that Italy would maintain neutrality, he decided to delay it. In response to British requests for direct negotiations to avoid war, Germany made demands on Poland, which served as

2940-588: The Anglo-German Naval Agreement and the German–Polish declaration of non-aggression . The situation became a crisis in late August as German troops continued to mobilise against the Polish border. On 23 August the Soviet Union signed a non-aggression pact with Germany, after tripartite negotiations for a military alliance between France, the United Kingdom, and Soviet Union had stalled. This pact had

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3080-662: The British Empire , with fighting in the Balkans , Mediterranean, and Middle East , the aerial Battle of Britain and the Blitz , and naval Battle of the Atlantic . Through a series of campaigns and treaties, Germany took control of much of continental Europe and formed the Axis alliance with Italy , Japan , and other countries. In June 1941, Germany led the European Axis in an invasion of

3220-566: The German Revolution of 1918–1919 , and a democratic government, later known as the Weimar Republic , was created. The interwar period saw strife between supporters of the new republic and hardline opponents on both the political right and left. Italy, as an Entente ally, had made some post-war territorial gains; however, Italian nationalists were angered that the promises made by the United Kingdom and France to secure Italian entrance into

3360-758: The German invasion of Poland and the United Kingdom and France 's declaration of war on Germany two days later on 3 September 1939. Dates for the beginning of the Pacific War include the start of the Second Sino-Japanese War on 7 July 1937, or the earlier Japanese invasion of Manchuria , on 19 September 1931. Others follow the British historian A. J. P. Taylor , who stated that the Sino-Japanese War and war in Europe and its colonies occurred simultaneously, and

3500-567: The Italian mainland , and Allied offensives in the Pacific—cost the Axis powers their initiative and forced them into strategic retreat on all fronts. In 1944, the Western Allies invaded German-occupied France at Normandy , while the Soviet Union regained its territorial losses and pushed Germany and its allies westward. At the same time, Japan suffered reversals in mainland Asia, while the Allies crippled

3640-537: The Japanese Navy and captured key islands . The war in Europe concluded with the liberation of German-occupied territories ; the invasion of Germany by the Western Allies and the Soviet Union, culminating in the fall of Berlin to Soviet troops; Hitler's suicide ; and the German unconditional surrender on 8 May 1945 . Following the refusal of Japan to surrender on the terms of the Potsdam Declaration ,

3780-411: The Knickebein headache were codenamed "Aspirin". Initially, modified medical diathermy sets transmitted interference. Later, local radio transmitters broadcast an extra "dot signal" at low power on nights where raids were expected. The German practice of turning on the beams long before the bombers reached the target area aided the British efforts. Avro Ansons fitted with receivers would be flown around

3920-682: The League of Nations as a force to preserve peace. Both Italy and Ethiopia were member nations, but the League did little when the former clearly violated Article X of the League's Covenant . The United Kingdom and France supported imposing sanctions on Italy for the invasion, but the sanctions were not fully enforced and failed to end the Italian invasion. Italy subsequently dropped its objections to Germany's goal of absorbing Austria . When civil war broke out in Spain, Hitler and Mussolini lent military support to

4060-693: The Nationalist rebels , led by General Francisco Franco . Italy supported the Nationalists to a greater extent than the Nazis: Mussolini sent more than 70,000 ground troops, 6,000 aviation personnel, and 720 aircraft to Spain. The Soviet Union supported the existing government of the Spanish Republic . More than 30,000 foreign volunteers, known as the International Brigades , also fought against

4200-499: The Oder to Elbe distance equalled the Elbe to release point distance, a bomber flying at constant speed arrived at the release point as the moving hand reached zero, when the bombs were automatically released. X-Gerät operated at a much higher frequency than Knickebein (around 60 MHz) and thus required the use of new radio equipment. There was not enough equipment to fit all bombers, so

4340-677: The Rome–Berlin Axis . A month later, Germany and Japan signed the Anti-Comintern Pact , which Italy joined the following year. The Kuomintang (KMT) party in China launched a unification campaign against regional warlords and nominally unified China in the mid-1920s, but was soon embroiled in a civil war against its former Chinese Communist Party (CCP) allies and new regional warlords . In 1931, an increasingly militaristic Empire of Japan , which had long sought influence in China as

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4480-545: The Second World War (1 September 1939 – 2 September 1945) was a global conflict between two coalitions: the Allies and the Axis powers . Nearly all the world's countries —including all the great powers —participated, with many investing all available economic, industrial, and scientific capabilities in pursuit of total war , blurring the distinction between military and civilian resources. Tanks and aircraft played major roles , with

4620-581: The Soviet–Japanese Neutrality Pact in April 1941. By contrast, the Germans were steadily making preparations for an attack on the Soviet Union, massing forces on the Soviet border. Hitler believed that the United Kingdom's refusal to end the war was based on the hope that the United States and the Soviet Union would enter the war against Germany sooner or later. On 31 July 1940, Hitler decided that

4760-580: The Stresa Front in April 1935 in order to contain Germany, a key step towards military globalisation ; however, that June, the United Kingdom made an independent naval agreement with Germany, easing prior restrictions. The Soviet Union, concerned by Germany's goals of capturing vast areas of Eastern Europe , drafted a treaty of mutual assistance with France. Before taking effect, though, the Franco-Soviet pact

4900-689: The Sudetenland , an area of Czechoslovakia with a predominantly ethnic German population. Soon the United Kingdom and France followed the appeasement policy of British Prime Minister Neville Chamberlain and conceded this territory to Germany in the Munich Agreement , which was made against the wishes of the Czechoslovak government, in exchange for a promise of no further territorial demands. Soon afterwards, Germany and Italy forced Czechoslovakia to cede additional territory to Hungary, and Poland annexed

5040-682: The Tanggu Truce was signed in 1933. Thereafter, Chinese volunteer forces continued the resistance to Japanese aggression in Manchuria , and Chahar and Suiyuan . After the 1936 Xi'an Incident , the Kuomintang and CCP forces agreed on a ceasefire to present a united front to oppose Japan. The Second Italo-Ethiopian War was a brief colonial war that began in October 1935 and ended in May 1936. The war began with

5180-568: The Trans-Olza region of Czechoslovakia. Although all of Germany's stated demands had been satisfied by the agreement, privately Hitler was furious that British interference had prevented him from seizing all of Czechoslovakia in one operation. In subsequent speeches Hitler attacked British and Jewish "war-mongers" and in January 1939 secretly ordered a major build-up of the German navy to challenge British naval supremacy. In March 1939, Germany invaded

5320-554: The Treaty of Craiova . The loss of one-third of Romania's 1939 territory caused a coup against King Carol II, turning Romania into a fascist dictatorship under Marshal Ion Antonescu , with a course set towards the Axis in the hopes of a German guarantee. Meanwhile, German-Soviet political relations and economic co-operation gradually stalled, and both states began preparations for war. In April 1940, Germany invaded Denmark and Norway to protect shipments of iron ore from Sweden , which

5460-723: The United Kingdom and France to declare war on Germany. Poland was divided between Germany and the Soviet Union under the Molotov–Ribbentrop Pact , in which they had agreed on " spheres of influence " in Eastern Europe. In 1940, the Soviets annexed the Baltic states and parts of Finland and Romania . After the fall of France in June 1940, the war continued mainly between Germany and

5600-529: The Wehrmacht moved their forces to the East in May 1941, in preparation for the attack on the Soviet Union . The idea of beam radio navigation was developed during the 1930s, initially as a blind landing aid. The basic concept is to produce two directional radio signals that are aimed slightly to the left and right of a runway 's midline. Radio operators in the aircraft listen for these signals and determine which of

5740-632: The Wehrmacht rapidly advanced to the Channel and cut off the Allied forces in Belgium, trapping the bulk of the Allied armies in a cauldron on the Franco-Belgian border near Lille. The United Kingdom was able to evacuate a significant number of Allied troops from the continent by early June, although they had to abandon almost all their equipment. On 10 June, Italy invaded France , declaring war on both France and

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5880-480: The Weser beam and reached Rhine , the radio operator heard a brief signal and set up his equipment. This consisted of a special stop-clock with two hands. When the Oder signal was received the clock automatically started and the two hands simultaneously swept up from zero. When the Elbe signal was received, one hand stopped and the other reversed, sweeping back towards zero. The stopped hand indicated an accurate measurement of travel time from Oder to Elbe . Since

6020-466: The Wotan system badly. It operated at 45 MHz, which happened to be the frequency of the powerful-but-dormant BBC television transmitter at Alexandra Palace . All Jones had to do was arrange for the return signal to be received from the aircraft and then sent to Alexandra Palace for re-transmission. The combination of the two signals modified the phase shift, and thus the apparent transit delay. Initially,

6160-612: The aftermath of World War I and the rise of fascism in Europe and militarism in Japan . Key events leading up to the war included Japan's invasion of Manchuria , the Spanish Civil War , the outbreak of the Second Sino-Japanese War , and Germany's annexations of Austria and the Sudetenland . World War II is generally considered to have begun on 1 September 1939, when Nazi Germany , under Adolf Hitler , invaded Poland , prompting

6300-404: The reunification of East and West Germany to take place and resolved most post–World War   II issues. No formal peace treaty between Japan and the Soviet Union was ever signed, although the state of war between the two countries was terminated by the Soviet–Japanese Joint Declaration of 1956 , which also restored full diplomatic relations between them. World War I had radically altered

6440-451: The start of the war on 1 September 1939, Lufthansa and the German aircraft industry invested heavily in the development of commercial aviation, and in systems and methods that would improve safety and reliability. Considerable effort went into blind-landing aids which allowed aircraft to approach an airport at night or in foul weather. The primary system developed for this was the Lorenz system , developed by Johannes Plendl , which

6580-494: The Air Ministry, led by R. V. Jones , became aware of the system when the Royal Aircraft Establishment analysed a downed German bomber's Lorenz system and observed it was far more sensitive than required for a mere landing aid. Secretly recorded transcripts from German prisoner of war pilots indicated this may have been a bomb aiming aid. Winston Churchill had also been given Ultra intelligence from decrypted Enigma messages that mentioned 'bombing beams'. When Jones mentioned

6720-409: The Allies were attempting to cut off . Denmark capitulated after six hours , and despite Allied support , Norway was conquered within two months. British discontent over the Norwegian campaign led to the resignation of Prime Minister Neville Chamberlain , who was replaced by Winston Churchill on 10   May 1940. On the same day, Germany launched an offensive against France . To circumvent

6860-400: The Axis war against the Soviet Union, in Romania's case partially to recapture territory ceded to the Soviet Union . In early June 1940, the Italian Regia Aeronautica attacked and besieged Malta , a British possession. From late summer to early autumn, Italy conquered British Somaliland and made an incursion into British-held Egypt . In October, Italy attacked Greece , but the attack

7000-421: The Blitz , but largely ended in May 1941 after failing to significantly disrupt the British war effort. Using newly captured French ports, the German Navy enjoyed success against an over-extended Royal Navy , using U-boats against British shipping in the Atlantic . The British Home Fleet scored a significant victory on 27   May 1941 by sinking the German battleship Bismarck . In November 1939,

7140-465: The British to fool the Germans into dropping their bombs where they wanted them. A side effect was that as the German crews had been trained to navigate solely by the beams, many crews failed to find either the true equisignal or Germany again. Some Luftwaffe bombers even landed at RAF bases, believing they were back at base. As good as Knickebein was, it was never intended to be used in the long-range role. Plendl had been working for some time to produce

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7280-405: The European Axis declaring war on the US. Japan conquered much of coastal China and Southeast Asia , but its advances in the Pacific were halted in mid-1942 after its defeat in the naval Battle of Midway ; Germany and Italy were defeated in North Africa and at Stalingrad in the Soviet Union. Key setbacks in 1943—including German defeats on the Eastern Front, the Allied invasions of Sicily and

7420-403: The FAR 91 minimums, so long as their operation is conducted without hazard to persons or property on the surface. In all EU member states, the Standardised European Rules of the Air apply: these set out a minimum altitude of 150 m (500 ft) above any obstacle within a radius of 150 m (500 ft), except with permission, or when taking off or landing. If an aircraft is flying over

7560-410: The French possessions of Syria and Lebanon , assisted by the Free French . With the situation in Europe and Asia relatively stable, Germany, Japan, and the Soviet Union made preparations for war. With the Soviets wary of mounting tensions with Germany, and the Japanese planning to take advantage of the European War by seizing resource-rich European possessions in Southeast Asia , the two powers signed

7700-420: The German transmitters, making it impossible to tell which signal was which. In this case the navigators would receive the equisignal over a wide area, and navigation along the bomb line became impossible, with the aircraft drifting into the "dash area" and no way to correct for it. Thus the beam was seemingly "bent" away from the target. Eventually, the beams could be inclined by a controlled amount which enabled

7840-421: The Germans introduced a new system that worked on different principles, the Y-Gerät . Having guessed the nature of this system from a passing mention, the British had already deployed countermeasures that rendered the system useless almost as soon as it was used. The Germans eventually abandoned the entire concept of radio navigation over the UK, concluding the British would continue to successfully jam it. Before

7980-464: The Germans might give up on the entire concept. British monitors soon started receiving intelligence from Enigma decrypts referring to a new device known as Y-Gerät , which was also sometimes referred to as Wotan . Jones had already concluded the Germans used code names that were too descriptive, so he asked a specialist in the German language and literature at Bletchley Park about the word Wotan . The specialist realised Wotan referred to Wōden ,

8120-426: The Germans, and the last large operational unit of the Polish Army surrendered on 6   October . Despite the military defeat, Poland never surrendered; instead, it formed the Polish government-in-exile and a clandestine state apparatus remained in occupied Poland. A significant part of Polish military personnel evacuated to Romania and Latvia; many of them later fought against the Axis in other theatres of

8260-450: The Nationalists. Both Germany and the Soviet Union used this proxy war as an opportunity to test in combat their most advanced weapons and tactics. The Nationalists won the civil war in April 1939; Franco, now dictator, remained officially neutral during World War   II but generally favoured the Axis . His greatest collaboration with Germany was the sending of volunteers to fight on the Eastern Front . In July 1937, Japan captured

8400-410: The Netherlands. Knickebein was used in the early stages of the German night-bombing offensive and proved to be fairly effective, but the tactics for using the system in a widespread bombing effort were not yet developed, so much of the early German night bombing offensive was limited to area bombing. Efforts in Britain to block the Knickebein system required time to implement. British intelligence at

8540-676: The RAF invested heavily in navigation training, equipping their aircraft with various devices, including an astrodome for taking a star fix and giving the navigator room to do his calculations in an illuminated workspace. This system was put to use as soon as the war began and was initially regarded as successful. In reality, the early bombing effort was a complete failure, with the majority of bombs landing miles from their intended targets. The Luftwaffe continued to research accurate night bombing against smaller targets. Not depending on celestial navigation, they invested their efforts in radio navigation systems. The Luftwaffe concentrated on developing

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8680-452: The Royal Navy putting three Italian battleships out of commission after a carrier attack at Taranto , and neutralising several more warships at the Battle of Cape Matapan . Italian defeats prompted Germany to deploy an expeditionary force to North Africa; at the end of March 1941, Rommel 's Afrika Korps launched an offensive which drove back Commonwealth forces. In less than a month, Axis forces advanced to western Egypt and besieged

8820-423: The Soviet Union occupied the entire territories of Estonia, Latvia and Lithuania, as well as the Romanian regions of Bessarabia, Northern Bukovina, and the Hertsa region . In August 1940, Hitler imposed the Second Vienna Award on Romania which led to the transfer of Northern Transylvania to Hungary. In September 1940, Bulgaria demanded Southern Dobruja from Romania with German and Italian support, leading to

8960-421: The Soviet Union , opening the Eastern Front and initially making large territorial gains. Japan aimed to dominate East Asia and the Asia-Pacific , and by 1937 was at war with the Republic of China . In December 1941, Japan attacked American and British territories in Southeast Asia and the Central Pacific , including Pearl Harbor in Hawaii , which resulted in the US and the UK declaring war against Japan, and

9100-418: The Soviet Union and Mongolia . The Japanese doctrine of Hokushin-ron , which emphasised Japan's expansion northward, was favoured by the Imperial Army during this time. This policy would prove difficult to maintain in light of the Japanese defeat at Khalkin Gol in 1939, the ongoing Second Sino-Japanese War and ally Nazi Germany pursuing neutrality with the Soviets. Japan and the Soviet Union eventually signed

9240-575: The Soviet Union should be eliminated and aimed for the conquest of Ukraine , the Baltic states and Byelorussia . However, other senior German officials like Ribbentrop saw an opportunity to create a Euro-Asian bloc against the British Empire by inviting the Soviet Union into the Tripartite Pact. In November 1940, negotiations took place to determine if the Soviet Union would join the pact. The Soviets showed some interest but asked for concessions from Finland, Bulgaria, Turkey, and Japan that Germany considered unacceptable. On 18 December 1940, Hitler issued

9380-402: The US dropped the first atomic bombs on Hiroshima and Nagasaki on 6 and 9 August. Faced with an imminent invasion of the Japanese archipelago , the possibility of further atomic bombings, and the Soviet declaration of war against Japan and its invasion of Manchuria , Japan announced its unconditional surrender on 15 August and signed a surrender document on 2 September 1945 , marking

9520-424: The United Kingdom and France guaranteed their support for Polish independence ; when Italy conquered Albania in April 1939, the same guarantee was extended to the Kingdoms of Romania and Greece . Shortly after the Franco - British pledge to Poland, Germany and Italy formalised their own alliance with the Pact of Steel . Hitler accused the United Kingdom and Poland of trying to "encircle" Germany and renounced

9660-489: The United Kingdom attacked on 3   July in an attempt to prevent its seizure by Germany. The air Battle of Britain began in early July with Luftwaffe attacks on shipping and harbours . The German campaign for air superiority started in August but its failure to defeat RAF Fighter Command forced the indefinite postponement of the proposed German invasion of Britain . The German strategic bombing offensive intensified with night attacks on London and other cities in

9800-472: The United Kingdom, this is known as a "Traffic Service". In other countries, it is known as "Flight Information Service". In the United States and Canada, any certified pilot who meets specific recency of experience criteria may operate an airworthy aircraft under VFR. In the US, there are specific VFR cruising altitudes, based on the aircraft's course, to assist pilots in separating their aircraft while operating under visual flight above 3,000 ft above

9940-401: The United Kingdom. The Germans turned south against the weakened French army, and Paris fell to them on 14   June. Eight days later France signed an armistice with Germany ; it was divided into German and Italian occupation zones , and an unoccupied rump state under the Vichy Regime , which, though officially neutral, was generally aligned with Germany. France kept its fleet, which

10080-640: The United States was assisting China and the Western Allies, and had amended the Neutrality Act to allow "cash and carry" purchases by the Allies. In 1940, following the German capture of Paris, the size of the United States Navy was significantly increased . In September the United States further agreed to a trade of American destroyers for British bases . Still, a large majority of the American public continued to oppose any direct military intervention in

10220-544: The United States, California's Oakland ( KOAK ), Monterey ( KMRY ) and Santa Ana ( KSNA ) airports routinely grant temporary IFR clearance when a low coastal overcast forces instrument approaches , while the rest of the state is still under visual flight rules. For pilots without an instrument rating who cannot legally fly by instrument flight rules, the restrictions of VMC minima can be troublesome in locations where weather conditions can change suddenly and unexpectedly or when weather events are highly localized. For instance,

10360-421: The United States, Canada, and Australia, a pilot operating under VFR outside Class B, C, D airspace can request "flight following" from ATC, to receive continuous verbal updates on air traffic. This service is provided by ATC if workload permits, but it is an advisory service only. The responsibility for maintaining separation with other aircraft and proper navigation still remains with the pilot in command (PIC). In

10500-470: The United States, class A airspace is measured using flight levels , and begins at FL180 up to FL600, which is about 18,000 to 60,000 feet as measured using an altimeter at standard pressure (29.92 inHg, 1013 mbar). An exception to IFR-only flying in this airspace is the occasional allowance of sailplanes within designated wave windows which may be opened by air traffic control when high altitude flights are to be conducted into mountain lee waves . In

10640-590: The Yellow River ; this manoeuvre bought time for the Chinese to prepare their defences at Wuhan , but the city was taken by October. Japanese military victories did not bring about the collapse of Chinese resistance that Japan had hoped to achieve; instead, the Chinese government relocated inland to Chongqing and continued the war. In the mid-to-late 1930s, Japanese forces in Manchukuo had sporadic border clashes with

10780-612: The airspace in which the aircraft is operating. In some countries, VFR flight is permitted at night, and is known as night VFR . This is generally permitted only under more restrictive conditions, such as maintaining minimum safe altitudes , and may require additional training as a pilot at night may not be able to see and avoid obstacles. The VFR pilot is required to "see and avoid" obstacles and other aircraft. Pilots flying under VFR assume responsibility for their separation from all other aircraft and are generally not assigned routes or altitudes by air traffic control (ATC). Depending on

10920-522: The beam from Kleve, on 31.5 MHz. It subsequently located the cross beam from Stollberg (its origin was unknown prior to this flight). The radio operator and navigator were able to plot the path of the beams and discovered that they intersected above the Rolls-Royce engine factory at Derby , at that time the only factory producing the Merlin engine. It was subsequently realised that the argument over whether

11060-418: The beam slightly to the left and then slightly to the right of the centreline of the runway. The beams widened as they spread from the antennas, so there was an area directly off the runway approach where the two signals overlapped. The switch was timed so it spent longer on the right side of the antenna than the left. An aircraft approaching the airport would tune one of their radios to the Lorenz frequency. If

11200-597: The beams would bend around the Earth was entirely academic, as the transmitters were more or less in line-of-sight to high altitude bombers. British sceptics started regarding the system as proof that the German pilots were not as good as their own, who they believed could do without such systems. The Butt Report proved this to be wrong; aerial reconnaissance returned photographs of the RAF bombing raids, showing that they were rarely, if ever, anywhere near their targets. Efforts to block

11340-484: The beams would bend around the Earth. Jones saved the flight by pointing out that Churchill himself had ordered it, and he would make sure that the Prime Minister would learn who cancelled it. The crew were not told specifics, and were simply ordered to search for radio signals around 30 MHz having Lorenz characteristics and, if they found any, to determine their bearing. The flight took off and eventually flew into

11480-467: The bomber's altitude and speed increased, the threat from ground-based defences was greatly reduced. Planners believed that " the bomber will always get through ". The problem with night bombing is that the same limitations in visibility meant the bomb crew would have a difficult time finding their targets, especially a blacked-out target at night. Only the largest targets, cities, could be attacked with any probability of success. To support this mission,

11620-417: The bombs dropped were placed within 100 yards (91 m) of the mid-line of the Weser beam, spread along it for a few hundred yards. This was the sort of accuracy that even daytime bombing could rarely achieve. The raid on Coventry with full support from other units dropping on their flares almost destroyed the city centre. X-Gerät proved more difficult to stop than Knickebein . Initial defences against

11760-653: The bombs kilometres short of the target. Setting up this false beam proved very difficult as the Germans, learning from their mistakes with Knickebein , did not switch the X-Gerät beams on until as late as possible, making it much more difficult to arrange the "false Elbe " in time. As the British slowly gained the upper hand in the Battle of the Beams, they started considering what the next German system would entail. Since Germany's current approaches had been rendered useless, an entirely new system would have to be developed. Jones believed that if they could defeat this system quickly,

11900-507: The capital Nanking in December 1937. After the fall of Nanking, tens or hundreds of thousands of Chinese civilians and disarmed combatants were murdered by the Japanese . In March 1938, Nationalist Chinese forces won their first major victory at Taierzhuang , but then the city of Xuzhou was taken by the Japanese in May. In June 1938, Chinese forces stalled the Japanese advance by flooding

12040-473: The category of airspace in which the flight is being conducted, VFR aircraft may be required to have a transponder to help Air Traffic Control identify the aircraft on radar in order that ATC can provide separation to IFR aircraft. Meteorological conditions that meet the minimum requirements for VFR flight are termed visual meteorological conditions (VMC). If they are not met, the conditions are considered instrument meteorological conditions (IMC), and

12180-470: The centerline of a factory deep in England. Tipped off about the system's operation by pre-war military intelligence , the British responded by sending their own Morse code signals so that the aircraft crew believed they were always properly centred in the beam while they flew wildly off course. The Germans became convinced the British had somehow learned to bend radio signals. When the problem became widespread,

12320-403: The conflict well into 1941. In December 1940, Roosevelt accused Hitler of planning world conquest and ruled out any negotiations as useless, calling for the United States to become an " arsenal of democracy " and promoting Lend-Lease programmes of military and humanitarian aid to support the British war effort; Lend-Lease was later extended to the other Allies, including the Soviet Union after it

12460-411: The country to find the beams' location to be reported to nearby broadcasters. The low-power "dot signal" was initially transmitted essentially at random, so German navigators would hear two dots. This meant there were many equisignal areas, and no easy way to distinguish them except by comparing them with a known location. The British transmitters were later modified to send their dots at the same time as

12600-515: The creation of a " New Roman Empire ". Adolf Hitler , after an unsuccessful attempt to overthrow the German government in 1923, eventually became the Chancellor of Germany in 1933 when Paul von Hindenburg and the Reichstag appointed him. Following Hindenburg's death in 1934, Hitler proclaimed himself Führer of Germany and abolished democracy, espousing a radical, racially motivated revision of

12740-410: The crew was on the left side of the centreline, they would hear a series of short tones followed by long pauses, meaning the aircraft was on the "dot" side of the antenna. Hearing the "dots", they would know that they had to veer to the right to fly down the centreline. If the crew was on the right side of the centerline, they would hear a series of long tones followed by short pauses, meaning the aircraft

12880-425: The directive to prepare for an invasion of the Soviet Union. Visual flight rules If the weather is less than VMC, pilots are required to use instrument flight rules , and operation of the aircraft will be primarily through referencing the instruments rather than visual reference. In a control zone , a VFR flight may obtain a clearance from air traffic control to operate as Special VFR . VFR requires

13020-739: The dissolution of the Austro-Hungarian, Ottoman, and Russian Empires. To prevent a future world war, the League of Nations was established in 1920 by the Paris Peace Conference . The organisation's primary goals were to prevent armed conflict through collective security, military, and naval disarmament , as well as settling international disputes through peaceful negotiations and arbitration. Despite strong pacifist sentiment after World War   I , irredentist and revanchist nationalism had emerged in several European states. These sentiments were especially marked in Germany because of

13160-637: The end of May completed the German conquest of the Balkans. Partisan warfare subsequently broke out against the Axis occupation of Yugoslavia , which continued until the end of the war. In the Middle East in May, Commonwealth forces quashed an uprising in Iraq which had been supported by German aircraft from bases within Vichy-controlled Syria . Between June and July, British-led forces invaded and occupied

13300-463: The end of the war. World War II changed the political alignment and social structure of the world, and it set the foundation of international relations for the rest of the 20th century and into the 21st century. The United Nations was established to foster international cooperation and prevent conflicts, with the victorious great powers—China, France, the Soviet Union, the UK, and the US—becoming

13440-430: The experimental unit Kampfgruppe 100 ( KGr 100) was given the task of using their X-Gerät equipment to guide other aircraft to the target. To do this, KGr 100 aircraft would attack as a small group first, dropping flares which other aircraft would then see and bomb visually. This is the first use of the pathfinder concept that the RAF improved to great effect against the Germans some three years later. The system

13580-526: The feedback. The Luftwaffe, finally realising that the British had been deploying countermeasures from the very first day that the system was used operationally, completely lost faith in electronic navigation aids as the British had predicted, and did not deploy any further system against Great Britain, although by this time Hitler's attention was turning towards Eastern Europe. Second World War Asia-Pacific Mediterranean and Middle East Other campaigns Coups World War II or

13720-566: The first step of what its government saw as the country's right to rule Asia , staged the Mukden incident as a pretext to invade Manchuria and establish the puppet state of Manchukuo . China appealed to the League of Nations to stop the Japanese invasion of Manchuria. Japan withdrew from the League of Nations after being condemned for its incursion into Manchuria. The two nations then fought several battles, in Shanghai , Rehe and Hebei , until

13860-843: The former Chinese imperial capital of Peking after instigating the Marco Polo Bridge incident , which culminated in the Japanese campaign to invade all of China. The Soviets quickly signed a non-aggression pact with China to lend materiel support, effectively ending China's prior cooperation with Germany . From September to November, the Japanese attacked Taiyuan , engaged the Kuomintang Army around Xinkou , and fought Communist forces in Pingxingguan . Generalissimo Chiang Kai-shek deployed his best army to defend Shanghai , but after three months of fighting, Shanghai fell. The Japanese continued to push Chinese forces back, capturing

14000-431: The guidance beam at the point where the bombs should be dropped. The aerials could be rotated to make the beams from two transmitters cross over the target. The bombers would fly into the beam of one and ride it until they started hearing the tones from the other (on a second receiver). When the steady "on course" sound was heard from the second beam, they dropped their bombs. The first of these new Knickebein transmitters

14140-512: The invasion of the Ethiopian Empire (also known as Abyssinia ) by the armed forces of the Kingdom of Italy ( Regno d'Italia ), which was launched from Italian Somaliland and Eritrea . The war resulted in the military occupation of Ethiopia and its annexation into the newly created colony of Italian East Africa ( Africa Orientale Italiana , or AOI); in addition it exposed the weakness of

14280-677: The latter enabling the strategic bombing of population centres and delivery of the only two nuclear weapons ever used in war. World War II was the deadliest conflict in history, resulting in 70 to 85 million deaths , more than half being civilians. Millions died in genocides , including the Holocaust of European Jews, as well as from massacres, starvation, and disease. Following the Allied powers' victory, Germany , Austria , Japan , and Korea were occupied, and war crimes tribunals were conducted against German and Japanese leaders . The causes of World War II included unresolved tensions in

14420-440: The modified jammers were able to successfully disrupt a raid on Birmingham on 19 November. X-Gerät was eventually defeated in another manner, by way of a "false Elbe " which was set up to cross the 'Weser' guide beam at a mere 1 kilometre (0.6 mi) after the Oder beam — much earlier than the expected 5 kilometres (3.1 mi). Since the final stages of the release were automatic, the clock would reverse prematurely and drop

14560-472: The operating principle based on the name Wotan was entirely by luck. Later documents showed that the original X-Gerät was known as Wotan I, and the Y-Gerät as Wotan II. Had he known the name was also associated with X-Gerät it was unlikely he would have concluded the system used a single beam. The British were ready for this system even before it was used. By chance, the Germans had chosen the operating frequency of

14700-497: The permanent members of its security council . The Soviet Union and the United States emerged as rival superpowers , setting the stage for the Cold War . In the wake of European devastation, the influence of its great powers waned, triggering the decolonisation of Africa and Asia . Most countries whose industries had been damaged moved towards economic recovery and expansion . World War II began in Europe on 1 September 1939 with

14840-519: The pilot must be flying in VMC by the time they leave the surface footprint of the controlled airspace (otherwise they would be flying VFR in IMC which is illegal). VFR flight is not allowed in airspace known as class A , regardless of the meteorological conditions except after failure of two way radio communications or during declared emergencies such as VFR traffic attempting to avoid severe weather formations. In

14980-413: The pilot. To avoid these scenarios, VFR flights intending to land at or take off from an airport experiencing localized conditions marginally below VMC minima may request Special VFR clearance from the tower. SVFR flight is only allowed while within the portion of an airport's controlled airspace (class B, C, or D) that extends to the surface, and it must be explicitly requested by the pilot and granted by

15120-571: The political European map with the defeat of the Central Powers —including Austria-Hungary , Germany , Bulgaria , and the Ottoman Empire —and the 1917 Bolshevik seizure of power in Russia , which led to the founding of the Soviet Union. Meanwhile, the victorious Allies of World War I , such as France, Belgium, Italy, Romania, and Greece, gained territory, and new nation-states were created out of

15260-583: The port of Tobruk . By late March 1941, Bulgaria and Yugoslavia signed the Tripartite Pact ; however, the Yugoslav government was overthrown two days later by pro-British nationalists. Germany and Italy responded with simultaneous invasions of both Yugoslavia and Greece , commencing on 6 April 1941; both nations were forced to surrender within the month. The airborne invasion of the Greek island of Crete at

15400-543: The possibility of bombing beams to Churchill, he ordered further investigation. The British codenamed the system Headache. Many in the Air Ministry did not believe that the system was in use. Frederick Lindemann , leading scientific adviser to the government, argued that any such system would not be able to follow the curvature of the Earth, although T. S. Eckersley of the Marconi company had said it could. Eckersley's assertion

15540-412: The release point. The Oder beam intersected Weser 10 kilometres (6.2 mi) before the release point, or 5 kilometres (3.1 mi) before Elbe . Rhine did not require the same precision and was approximately 30 kilometres (18.6 mi) before the release point. The beams' width added a small error to the intersection coordinates, on the order of tens to hundreds of meters. As the bomber followed

15680-693: The remainder of Czechoslovakia and subsequently split it into the German Protectorate of Bohemia and Moravia and a pro-German client state , the Slovak Republic . Hitler also delivered an ultimatum to Lithuania on 20 March 1939, forcing the concession of the Klaipėda Region , formerly the German Memelland . Greatly alarmed and with Hitler making further demands on the Free City of Danzig ,

15820-588: The same in the UK as the rest of the EU CVFR flight is used in locations where aviation authorities have determined that VFR flight should be allowed, but that ATC separation and minimal guidance are necessary. In this respect, CVFR is similar to instrument flight rules (IFR) in that ATC will give pilots headings and altitudes at which to fly, and will provide separation and conflict resolution. However, pilots and aircraft do not need to be IFR rated to fly in CVFR areas, which

15960-435: The signal was re-transmitted at low power, not powerful enough for the Germans to realise what was happening, but enough to spoil the accuracy of the system. Over subsequent nights, the transmitter power was gradually increased. As Y-Gerät ' s use went on, the aircrew accused the ground station of sending bad signals and the ground station alleged the aircraft had loose connections. The whole scheme appealed to Jones as he

16100-410: The significant territorial, colonial, and financial losses imposed by the Treaty of Versailles . Under the treaty, Germany lost around 13 percent of its home territory and all its overseas possessions , while German annexation of other states was prohibited, reparations were imposed, and limits were placed on the size and capability of the country's armed forces . The German Empire was dissolved in

16240-483: The simple switching of two of the reflector elements to alter the beam directions very marginally. The beam angles were so dramatically reduced that it was only a few tens of yards wide over the target. It was the shape of the aerials that gave the system its code name, Knickebein , which means "crooked leg", although the word is also the name of a magical raven in Germanic mythology . For the required range, transmitted power

16380-494: The start or prelude to World War II. The exact date of the war's end also is not universally agreed upon. It was generally accepted at the time that the war ended with the armistice of 15 August 1945 ( V-J Day ), rather than with the formal surrender of Japan on 2 September 1945, which officially ended the war in Asia . A peace treaty between Japan and the Allies was signed in 1951. A 1990 treaty regarding Germany's future allowed

16520-575: The strong Maginot Line fortifications on the Franco-German border, Germany directed its attack at the neutral nations of Belgium , the Netherlands , and Luxembourg . The Germans carried out a flanking manoeuvre through the Ardennes region, which was mistakenly perceived by the Allies as an impenetrable natural barrier against armoured vehicles. By successfully implementing new Blitzkrieg tactics,

16660-666: The surface (AGL) but below 18,000 ft Mean Sea Level (MSL). Unofficially, most pilots use these rules at all levels of cruise flight. FAR 91.159 states that any aircraft: In the US, FAR Part 91 (specifically 91.119 ) of the Federal Aviation Regulations controls the minimum safe altitudes by which aircraft can be operated in the National Airspace System . Other aircraft, such as helicopters, powered parachutes, and weight-shift-control aircraft, are not required to meet

16800-452: The system were deployed in a similar fashion to Knickebein in an attempt to disrupt the Coventry raid but proved to be a failure. Although Jones had correctly guessed the beam layout (and acknowledges it was only a guess), the modulation frequency had been measured incorrectly as 1,500 Hz, but was in fact 2,000 Hz. At the time it was believed that this would not make any difference, as

16940-460: The tones were close enough that an operator would have a hard time distinguishing them in a noisy aircraft. The mystery was eventually revealed after an X-Gerät -equipped Heinkel He 111 crashed on 6 November 1940 on the English coast at West Bay , Bridport. Although the aircraft sank during the recovery operation, the waterlogged X-Gerät equipment was recovered. On examination, it was learned that

17080-474: The tower (some airports, primarily large Class B facilities, do not allow SVFR operation in their airspace at all). Visibility on the ground must still be greater than one statute mile, but most other VMC minima such as ceiling are waived. The pilot is required to maintain VFR separation distances from other aircraft and, by requesting SVFR, asserts that they can do so despite the marginal conditions. For departing flights,

17220-429: The transit time of the signal, and hence the distance to the aircraft. Coupled with the direction of the beam (adjusted for a maximum return signal), the bomber's position could be established with considerable accuracy. The bombers did not have to track the beam, instead the ground controllers could calculate it and then give radio instructions to the pilot to correct the flight path. Jones later learned that his guess on

17360-460: The two beams they are flying in. This is normally accomplished by sending Morse code signals into the two beams, to identify right and left. For bombing, the Luftwaffe built huge versions of the antennas to provide much greater accuracy at long range, named Knickebein and X-Gerät . These were used during the early stages of " The Blitz " with great effect, in one case laying a strip of bombs down

17500-510: The two wars became World War II in 1941. Other proposed starting dates for World War II include the Italian invasion of Abyssinia on 3 October 1935. The British historian Antony Beevor views the beginning of World War   II as the Battles of Khalkhin Gol fought between Japan and the forces of Mongolia and the Soviet Union from May to September 1939. Others view the Spanish Civil War as

17640-504: The war were not fulfilled in the peace settlement. From 1922 to 1925, the Fascist movement led by Benito Mussolini seized power in Italy with a nationalist, totalitarian , and class collaborationist agenda that abolished representative democracy, repressed socialist, left-wing, and liberal forces, and pursued an aggressive expansionist foreign policy aimed at making Italy a world power, promising

17780-475: The war. Germany annexed western Poland and occupied central Poland ; the Soviet Union annexed eastern Poland ; small shares of Polish territory were transferred to Lithuania and Slovakia . On 6 October, Hitler made a public peace overture to the United Kingdom and France but said that the future of Poland was to be determined exclusively by Germany and the Soviet Union. The proposal was rejected and Hitler ordered an immediate offensive against France, which

17920-503: The west halted the German advance for several days, but it was outflanked and encircled by the Wehrmacht . Remnants of the Polish army broke through to besieged Warsaw . On 17 September 1939, two days after signing a cease-fire with Japan , the Soviet Union invaded Poland under the supposed pretext that the Polish state had ceased to exist. On 27 September, the Warsaw garrison surrendered to

18060-687: The world order , and soon began a massive rearmament campaign . France, seeking to secure its alliance with Italy, allowed Italy a free hand in Ethiopia , which Italy desired as a colonial possession. The situation was aggravated in early 1935 when the Territory of the Saar Basin was legally reunited with Germany, and Hitler repudiated the Treaty of Versailles, accelerated his rearmament programme, and introduced conscription. The United Kingdom, France and Italy formed

18200-614: Was invaded by Germany. The United States started strategic planning to prepare for a full-scale offensive against Germany. At the end of September 1940, the Tripartite Pact formally united Japan, Italy, and Germany as the Axis powers . The Tripartite Pact stipulated that any country—with the exception of the Soviet Union—that attacked any Axis Power would be forced to go to war against all three. The Axis expanded in November 1940 when Hungary , Slovakia , and Romania joined. Romania and Hungary later made major contributions to

18340-437: Was a natural practical joker, and remarked that he was able to play one of the largest practical jokes with virtually any national resource that he required. The gradually increasing power conditioned the Germans such they did not realise that the system was being interfered with, but believed that it suffered several inherent defects. Eventually, as the power was increased enough, the whole Y-Gerät system started to ring with all

18480-498: Was eventually demonstrated after Churchill ordered a flight to try to detect the beams. The RAF lacked equipment capable of detecting 30–33 MHz Lorenz signals, so they purchased an American Hallicrafters S-27 amateur radio receiver from a shop in Lisle Street, London. The receiver was fitted into an Avro Anson and operated by a member of the Y Service . The flight was nearly cancelled when Eckersley withdrew his assertion that

18620-407: Was first tested on 20 December 1939 when a bomber from KGr 100 flown by Oberleutnant Hermann Schmidt flew over London at 7,000m (23,000 ft). X-Gerät was used effectively in a series of raids known to the Germans as Moonlight Sonata, against Coventry , Wolverhampton and Birmingham . In the raid on Birmingham only KGr 100 was used and British post-raid analysis showed that the vast majority of

18760-414: Was in the process of being widely deployed on large civilian and military aircraft. The Lorenz system worked by feeding a special three-element antenna system with a modulated radio signal. The signal was fed to the centre dipole , which had a slightly longer reflector element on either side set slightly back. A switch rapidly alternated the opened midpoint connection of each reflector in turn, sending

18900-501: Was increased considerably. The Knickebein receivers were disguised as a standard blind landing receiver system, consisting apparently of the EBL-1 and the EBL-2 receivers. The beam from a single transmitter would guide the bombers towards the target, but could not tell them when they were over it. To add this ranging feature, a second transmitter similar to the first was set up so its beam crossed

19040-436: Was on the "dash" side of the antenna. Hearing the "dashes", they would know that they had to veer to the left to fly down the centreline. In the centre, the radio would receive both signals, where the dots filled in the gaps in the dashes and produced a continual signal, the so-called "equisignal". Flying in the known direction of the runway and keeping the equisignal on the radio, Lorenz-equipped crews could guide an aircraft down

19180-452: Was postponed until the spring of 1940 due to bad weather. After the outbreak of war in Poland, Stalin threatened Estonia , Latvia , and Lithuania with military invasion, forcing the three Baltic countries to sign pacts allowing the creation of Soviet military bases in these countries; in October 1939, significant Soviet military contingents were moved there. Finland refused to sign

19320-761: Was repulsed with heavy Italian casualties; the campaign ended within months with minor territorial changes. To assist Italy and prevent Britain from gaining a foothold, Germany prepared to invade the Balkans, which would threaten Romanian oil fields and strike against British dominance of the Mediterranean. In December 1940, British Empire forces began counter-offensives against Italian forces in Egypt and Italian East Africa . The offensives were successful; by early February 1941, Italy had lost control of eastern Libya, and large numbers of Italian troops had been taken prisoner. The Italian Navy also suffered significant defeats, with

19460-595: Was required to go through the bureaucracy of the League of Nations, which rendered it essentially toothless. The United States, concerned with events in Europe and Asia, passed the Neutrality Act in August of the same year. Hitler defied the Versailles and Locarno Treaties by remilitarising the Rhineland in March 1936, encountering little opposition due to the policy of appeasement . In October 1936, Germany and Italy formed

19600-611: Was set up in 1939 on Stollberg hill in Nordfriesland near the border with Denmark ; at Kleve (Cleves) near the Dutch border, almost the most westerly point in Germany, and at Lörrach near the border with France and Switzerland in south-western Germany. Following the fall of France in June 1940, additional transmitters were installed on the French coast. Stations were also constructed in Norway and

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