133-465: The Waller Gunnery Trainer was a simulator for training World War II aerial gunners using multiple film projectors. Its inventor, Fred Waller , later invented the Cinerama film format. This military -related article is a stub . You can help Misplaced Pages by expanding it . World War II Asia-Pacific Mediterranean and Middle East Other campaigns Coups World War II or
266-637: 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
399-564: 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
532-621: A German takeover. It was in these circumstances that Winston Churchill, who had become Prime Minister on 10 May 1940, first wrote to President Franklin Roosevelt to request the loan of fifty obsolescent US Navy destroyers. This eventually led to the " Destroyers for Bases Agreement " (effectively a sale but portrayed as a loan for political reasons), which operated in exchange for 99-year leases on certain British bases in Newfoundland , Bermuda and
665-419: A disaster within days. On 14 September 1939, Britain's most modern carrier, HMS Ark Royal , narrowly avoided being sunk when three torpedoes from U-39 exploded prematurely. U-39 was forced to surface and scuttle by the escorting destroyers, becoming the first U-boat loss of the war. Another carrier, HMS Courageous , was sunk three days later by U-29 . German success in sinking Courageous
798-982: A flotilla of 27 Italian submarines operated from the BETASOM base in Bordeaux to attack Allied shipping in the Atlantic, initially under the command of Rear Admiral Angelo Parona , then of Rear Admiral Romolo Polacchini and finally of Ship-of-the-Line Captain Enzo Grossi . The Italian submarines had been designed to operate in a different way than U-boats, and they had a number of flaws that needed to be corrected (for example huge conning towers, slow speed when surfaced, lack of modern torpedo fire control), which meant that they were ill-suited for convoy attacks, and performed better when hunting down isolated merchantmen on distant seas, taking advantage of their superior range and living standards. While initial operation met with little success (only 65343 GRT sunk between August and December 1940),
931-584: A major part of the naval history of World War II . At its core was the Allied naval blockade of Germany , announced the day after the declaration of war, and Germany's subsequent counter-blockade. The campaign peaked from mid-1940 through to the end of 1943. The Battle of the Atlantic pitted U-boats and other warships of the German Kriegsmarine (Navy) and aircraft of the Luftwaffe (Air Force) against
1064-462: A patrol line of U-boats searched for a convoy and when one was found all U-boats converged and attacked together at night on the surface. Neither aircraft nor early forms of Sonar , (called ASDIC by the British), were considered a serious threat at the time. ASDIC could not detect a surfaced submarine and its range was less than that of an electric torpedo , aircraft could not operate at night and, during
1197-514: 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
1330-715: 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
1463-434: A raider hunting for independently sailing ships, and to avoid combat with superior forces. The Anglo-German Naval Agreement of 1935 allowed Hitler to renounce the treaty of Versailles, and to build a fleet 35% the size of Britain's fleet. A building program for four battleships, two aircraft carriers, five heavy cruisers, destroyers and U-boats was immediately initiated. With the agreement, Hitler thought that conflict with
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#17330856420031596-469: 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
1729-743: 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,
1862-416: A theatre covering millions of square miles of ocean. The situation changed constantly, with one side or the other gaining advantage, as participating countries surrendered, joined and even changed sides in the war, and as new weapons, tactics, counter-measures and equipment were developed by both sides. The Allies gradually gained the upper hand, overcoming German surface-raiders by the end of 1942 and defeating
1995-519: 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
2128-588: 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
2261-662: 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
2394-764: The First World War , countries tried to limit or abolish submarines. The effort failed. Instead, the London Naval Treaty required submarines to abide by " cruiser rules ", which demanded they surface, search and place ship crews in "a place of safety" (for which lifeboats did not qualify, except under particular circumstances) before sinking them, unless the ship in question showed "persistent refusal to stop...or active resistance to visit or search". These regulations did not prohibit arming merchantmen, but doing so, or having them report contact with submarines (or raiders ), made them de facto naval auxiliaries and removed
2527-566: 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
2660-814: 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
2793-567: 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
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#17330856420032926-537: 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 ,
3059-682: 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
3192-693: 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
3325-677: 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
3458-539: The Royal Navy , Royal Canadian Navy , United States Navy , and Allied merchant shipping. Convoys , coming mainly from North America and predominantly going to the United Kingdom and the Soviet Union , were protected for the most part by the British and Canadian navies and air forces. These forces were aided by ships and aircraft of the United States beginning September 13, 1941. The Germans were joined by submarines of
3591-603: 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
3724-581: 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
3857-580: 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
3990-689: 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
4123-682: 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
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4256-568: 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
4389-554: 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
4522-669: 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
4655-683: 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
4788-773: The West Indies , a financially advantageous bargain for the United States but militarily beneficial for Britain, since it effectively freed up British military assets to return to Europe. A significant percentage of the US population opposed entering the war, and some American politicians (including the US Ambassador to Britain, Joseph P. Kennedy ) believed that Britain and its allies might actually lose. The first of these destroyers were only taken over by their British and Canadian crews in September, and all needed to be rearmed and fitted with ASDIC. It
4921-451: 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
5054-426: The metric bands , lacked target discrimination and range. Moreover, corvettes were too slow to catch a surfaced U-boat. Pack tactics were first used successfully in September and October 1940 to devastating effect, in a series of convoy battles. On September 21, convoy HX 72 of 42 merchantmen was attacked by a pack of four U-boats, which sank eleven ships and damaged two over the course of two nights. In October,
5187-404: 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
5320-571: The Allied convoys singly, U-boats were directed to work in wolf packs ( Rudel ) coordinated by radio. The boats spread out into a long patrol line that bisected the path of the Allied convoy routes. Once in position, the crew studied the horizon through binoculars looking for masts or smoke, or used hydrophones to pick up propeller noises. When one boat sighted a convoy, it would report the sighting to U-boat headquarters , shadowing and continuing to report as needed until other boats arrived, typically at night. Instead of being faced by single submarines,
5453-409: 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
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5586-405: The Atlantic were Carlo Fecia di Cossato , commander of the submarine Enrico Tazzoli , and Gianfranco Gazzana-Priaroggia , commander of Archimede and then of Leonardo da Vinci . Despite their success, U-boats were still not recognised as the foremost threat to the North Atlantic convoys. With the exception of men like Dönitz, most naval officers on both sides regarded surface warships as
5719-404: The Atlantic", which he compared to the Battle of France , fought the previous summer. The first meeting of the Cabinet's "Battle of the Atlantic Committee" was on March 19. Churchill claimed to have coined the phrase "Battle of the Atlantic" shortly before Alexander's speech, but there are several examples of earlier usage. Following the use of unrestricted submarine warfare by Germany in
5852-454: The Atlantic. The power of a raider against a convoy was demonstrated by the fate of convoy HX 84 , attacked by the pocket battleship Admiral Scheer on 5 November 1940. Admiral Scheer quickly sank five ships and damaged several others as the convoy scattered. Only the sacrifice of the escorting armed merchant cruiser HMS Jervis Bay (whose commander, Edward Fegen , was awarded a posthumous Victoria Cross ) and failing light allowed
5985-433: The Axis attempt to stem the flow of merchant shipping that enabled Britain to keep fighting. Rationing in the United Kingdom was also used with the aim of reducing demand, by reducing wastage and increasing domestic production and equality of distribution. From 1942 onward, the Axis also sought to prevent the build-up of Allied supplies and equipment in the UK in preparation for the invasion of occupied Europe . The defeat of
6118-400: 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
6251-547: The Battle of the Atlantic from 1941 onwards. These were primarily Fw 200 Condors. The Condors also bombed convoys that were beyond land-based fighter cover and thus defenceless. Initially, the Condors were very successful, claiming 365,000 tons of shipping in early 1941. These aircraft were few in number, however, and directly under Luftwaffe control; in addition, the pilots had little specialised training for anti-shipping warfare, limiting their effectiveness. The Germans received help from their allies. From August 1940,
6384-421: 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,
6517-420: The British Naval Cypher No. 3, allowing the Germans to estimate where and when convoys could be expected. In response, the British applied the techniques of operations research to the problem and came up with some counter-intuitive solutions for protecting convoys. They realised that the area of a convoy increased by the square of its perimeter, meaning the same number of ships, using the same number of escorts,
6650-399: The British admiralty failed to appreciate the limitations of ASDIC: range was limited, ASDIC worked only well if the speed of the operating vessel was below eight knots, ASDIC was hampered by rough weather and it took a very skilled operator to distinguish echoes from thermoclines , whales, shoals of fish and wrecks. Also, early versions could not look directly down, so contact was lost during
6783-400: The British and French immediately began a blockade of Germany , although this had little immediate effect on German industry. The Royal Navy quickly introduced a convoy system for the protection of trade that gradually extended out from the British Isles, eventually reaching as far as Panama , Bombay and Singapore . Convoys allowed the Royal Navy to concentrate its escorts near the one place
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#17330856420036916-418: The British. According to his calculations, a fleet of 300 medium Type VII U-boats could sink a million tons of ships a month and within a year sink enough of the about 3,000 British merchant ships (comprising 17,5 million tons) to strangle the British economy. In the first world war, U-boats had been defeated mainly by the convoy system, but Dönitz thought this could be overcome with the Rudeltaktik :
7049-501: The Channel and along the east coast in defence of shipping lanes, and also offensive mine barrages on the German U-boat lanes toward the Atlantic Ocean. In 1939, the Kriegsmarine lacked the strength to challenge the combined British Royal Navy and French Navy ( Marine Nationale ) for command of the sea. Instead, German naval strategy relied on commerce raiding using capital ships , armed merchant cruisers , submarines and aircraft. Many German warships were already at sea when war
7182-405: 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
7315-410: 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
7448-408: The German U-boat torpedoes : both the impact pistol and the magnetic influence pistol (detonation mechanism) were defective, and the torpedoes did not run at the proper depth, often undershooting targets. Only one British warship was sunk by U-boats in more than 38 attacks. As the news spread through the U-boat fleet, it began to undermine morale . Since the effectiviness of the magnetic pistol
7581-420: The German tactics against the inadequate British anti-submarine methods. On 1 December, seven German and three Italian submarines caught HX 90 , sinking 10 ships and damaging three others. At the end of the year 1940, the Admiralty viewed the number of ships sunk with growing alarm. Damaged ships might survive but could be out of commission for long periods. Two million gross tons of merchant shipping—13% of
7714-464: The German war effort: Germany spent more money on producing naval vessels than it did every type of ground vehicle combined, including tanks. The Battle of the Atlantic has been called the "longest, largest, and most complex" naval battle in history. The campaign started immediately after the European war began, during the so-called " Phoney War ", and lasted more than five years, until the German surrender in May 1945. It involved thousands of ships in
7847-426: 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
7980-408: The Italian Regia Marina (Royal Navy) after Germany's Axis ally Italy entered the war on June 10, 1940. As an island country, the United Kingdom was highly dependent on imported goods. Britain required more than a million tons of imported material per week in order to survive and fight. In essence, the Battle of the Atlantic involved a tonnage war ; the Allied struggle to supply Britain, and
8113-428: The Italian intervention was not favourably regarded by Dönitz, who characterised Italians as "inadequately disciplined" and "unable to remain calm in the face of the enemy". They were unable to co-operate in wolf pack tactics or even reliably report contacts or weather conditions, and their area of operation was moved away from those of the Germans. Amongst the more successful Italian submarine commanders who operated in
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#17330856420038246-450: 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
8379-452: 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
8512-423: 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
8645-421: 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
8778-418: 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
8911-575: 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
9044-514: The U-boat threat was a prerequisite for pushing back the Axis in Western Europe. The outcome of the battle was a strategic victory for the Allies—the German tonnage war failed—but at great cost: 3,500 merchant ships and 175 warships were sunk in the Atlantic for the loss of 783 U-boats and 47 German surface warships, including 4 battleships ( Bismarck , Scharnhorst , Gneisenau , and Tirpitz ), 9 cruisers, 7 raiders, and 27 destroyers. This front ended up being highly significant for
9177-504: The U-boats by mid-1943, though losses due to U-boats continued until the war's end. British Prime Minister Winston Churchill later wrote "The only thing that really frightened me during the war was the U-boat peril. I was even more anxious about this battle than I had been about the glorious air fight called the ' Battle of Britain '." On 5 March 1941, the First Lord of the Admiralty , A. V. Alexander , asked Parliament for "many more ships and great numbers of men" to fight "the Battle of
9310-443: The U-boats were guaranteed to be found, the convoys. Each convoy consisted of between 30 and 70 mostly unarmed merchant ships. Some British naval officials, particularly the First Lord of the Admiralty, Winston Churchill , sought a more 'offensive' strategy. The Royal Navy formed anti-submarine hunting groups based on aircraft carriers to patrol the shipping lanes in the Western Approaches and hunt for German U-boats. This strategy
9443-412: The UK was very unlikely and hence the fleet was designed for commerce raiding against the French rather than to try to challenge command of the sea. The commander of the German U-boats, Karl Dönitz, had his own opinions. In contrast with Hitler and Raeder, the chief of the German Navy, he judged that war with the UK was inevitable and that not a large surface fleet was needed, but that U-boats could defeat
9576-453: 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
9709-568: 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
9842-538: 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
9975-455: 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
10108-640: 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
10241-590: 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
10374-573: The boats needed to return to harbour to refuel, re-arm, re-stock supplies, and refit. The harsh winter of 1939–40, which froze over many of the Baltic ports, seriously hampered the German offensive by trapping several new U-boats in the ice. Hitler's plans to invade Norway and Denmark in the spring of 1940 led to the withdrawal of the fleet's surface warships and most of the ocean-going U-boats for fleet operations in Operation Weserübung . The resulting Norwegian campaign revealed serious flaws in
10507-456: 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
10640-403: 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
10773-487: The convoy escorts then had to cope with groups of up to half a dozen U-boats attacking simultaneously. The most daring commanders, such as Kretschmer, penetrated the escort screen and attacked from within the columns of merchantmen. The escort vessels, which were too few in number and often lacking in endurance, had no answer to multiple submarines attacking on the surface at night, as their ASDIC worked well only against underwater targets. Early British marine radar, working in
10906-515: 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
11039-537: The day, an alert U-boat could dive before the aircraft attacked. Dönitz could not convince Raeder of his ideas, so each time the U-boat fleet was expanded, Raeder opted to build a mixture of coastal, medium and large submarines, even minelayers and U-cruisers. Even when in 1938 Hitler realised he would sooner or later have to oppose the UK and launched his Plan Z , only a minority of the planned 239 U-boats were medium U-boats. With
11172-456: The directive to prepare for an invasion of the Soviet Union. Battle of the Atlantic 1939 1940 1941 1942 1943 1944 1945 Asia-Pacific Mediterranean and Middle East Other campaigns Coups The Battle of the Atlantic , the longest continuous military campaign in World War II , ran from 1939 to the defeat of Nazi Germany in 1945, covering
11305-739: 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
11438-637: 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
11571-463: 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
11704-443: The final stages of a depth charge attack. The basic set could detect range and bearing, but target depth could only be estimated from the range at which contact was lost. An escort swept its ASDIC beam in an arc from one side of its course to the other, stopping the transducer every few degrees to send out a signal. On detection of a submarine, the escort would close in at moderate speed and increase its speed to attack. The intention
11837-566: 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
11970-578: The first three months of war. The British and French formed a series of hunting groups including three battlecruisers , three aircraft carriers, and 15 cruisers to seek the raider and her sister Deutschland , which was operating in the North Atlantic. These hunting groups had no success until Admiral Graf Spee was caught off the mouth of the River Plate between Argentina and Uruguay by an inferior British force. After suffering damage in
12103-665: The fleet available to the British—were under repair and unavailable, which had the same effect in slowing down cross-Atlantic supplies. Nor were the U-boats the only threat. Following some early experience in support of the war at sea during Operation Weserübung, the Luftwaffe began to take a toll of merchant ships. Martin Harlinghausen and his recently established command— Fliegerführer Atlantik —contributed small numbers of aircraft to
12236-843: 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
12369-554: The introduction of ASDIC, the British Admiralty believed to have effectively neutralized the submarine threat. Hence the number of destroyers and convoy escorts was reduced and the anti-submarine branch was seen as third rate. Although destroyers were also equipped with ASDIC, it was expected that these ships would be used in fleet actions rather than anti-submarine warfare, so they were not extensively trained in their use. Trials with ASDIC were usually conducted in ideal conditions and
12502-512: 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
12635-677: 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
12768-543: The number of U-boats on patrol in the Atlantic began to increase, the number of escorts available for the convoys was greatly reduced. The only consolation for the British was that the large merchant fleets of occupied countries like Norway and the Netherlands came under British control. After the German occupation of Denmark and Norway, Britain occupied Iceland and the Faroe Islands , establishing bases there and preventing
12901-582: The other merchantmen to escape. The British now suspended North Atlantic convoys, and the Home Fleet put to sea to try to intercept Admiral Scheer . The search failed and Admiral Scheer disappeared into the South Atlantic. She reappeared in the Indian Ocean the following month. Other German surface raiders now began to make their presence felt. On Christmas Day 1940, the cruiser Admiral Hipper attacked
13034-610: The other navies of the world combined. Similarly the role of aircraft had been neglected; the Royal Air Force had organised a Coastal Command to support the Royal Navy, but it possessed insufficient aircraft, had no long range aircraft nor were aircraft crew trained in anti-submarine warfare. The only weapon against submarines was inadequate bombs. Finally, it was not forgotten that in World War I, mines had sunk more U-boats than any other weapon. Plans were drafted for mine fields in
13167-497: 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
13300-571: 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
13433-583: 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
13566-521: The protection of the cruiser rules. The Treaty of Versailles forbade the Germans to operate U-boats and reduced the German surface fleet to a few obsolete ships. When three of these obsolete ships had to be replaced, the Germans opted to construct the Deutschland-class of panzerschiffe (armoured ships) or "pocket battleships" as they were nicknamed by foreign navies. These ships were designed for commerce raiding on distant seas, to operate as
13699-572: The rapid conquest of the Low Countries and France in May and June, and the Italian entry into the war on the Axis side in June transformed the war at sea in general and the Atlantic campaign in particular in three main ways: The completion of Hitler's campaign in Western Europe meant U-boats withdrawn from the Atlantic for the Norwegian campaign now returned to the war on trade. So at the very time
13832-693: 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 ,
13965-410: 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
14098-495: The situation improved gradually over time, and up to August 1943 the 32 Italian submarines that operated there sank 109 ships of 593,864 tons, for 17 subs lost in return, giving them a subs-lost-to-tonnage sunk ratio similar to Germany's in the same period, and higher overall. The Italians were also successful with their use of " human torpedo " chariots, disabling several British ships in Gibraltar. Despite these successes,
14231-419: The slow convoy SC 7 , with an escort of two sloops and two corvettes, was overwhelmed, losing 59% of its ships. The battle for HX 79 in the following days was in many ways worse for the escorts than for SC 7. The loss of a quarter of the convoy without any loss to the U-boats, despite a very strong escort (two destroyers, four corvettes, three trawlers, and a minesweeper) demonstrated the effectiveness of
14364-494: 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
14497-521: 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,
14630-429: The subsequent action, she took shelter in neutral Montevideo harbour and was scuttled on 17 December 1939. After this initial burst of activity, the Atlantic campaign quietened down. Admiral Karl Dönitz , commander of the U-boat fleet, had planned a maximum submarine effort for the first month of the war, with almost all the available U-boats out on patrol in September. That level of deployment could not be sustained;
14763-541: The threat of war became more clear it was realised that Britain could not rely on the London Naval Treaty that outlawed unrestricted submarine warfare. The organisational infrastructure for convoys had been maintained since World War I, with a thorough and systematic upgrade in the second half of the 1930s, but not enough escorts were available for convoy escorting, and a crash program for building Tree-class trawlers , Flower-class corvettes and Hunt-class destroyers
14896-475: The troop convoy WS 5A, but was driven off by the escorting cruisers. Admiral Hipper had more success two months later, on 12 February 1941, when she found the unescorted convoy SLS 64 of 19 ships and sank seven of them. In January 1941, the battleships Scharnhorst and Gneisenau put to sea from Germany to raid the shipping lanes in Operation Berlin . With so many German raiders at large in
15029-569: 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
15162-565: The ultimate commerce destroyers. For the first half of 1940, there were no German surface raiders in the Atlantic because the German Fleet had been concentrated for the invasion of Norway. The sole pocket battleship raider, Admiral Graf Spee , had been stopped at the Battle of the River Plate by an inferior and outgunned British squadron. From the summer of 1940 a small but steady stream of warships and armed merchant raiders set sail from Germany for
15295-504: 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
15428-475: 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
15561-503: 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
15694-687: 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
15827-614: 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
15960-434: Was a converted civilian airliner—a stop-gap solution for Fliegerführer Atlantik . Due to ongoing friction between the Luftwaffe and Kriegsmarine , the primary source of convoy sightings was the U-boats themselves. Since a submarine's bridge was very close to the water, their range of visual detection was quite limited. The best source proved to be the codebreakers of B-Dienst who had succeeded in deciphering
16093-430: Was already reduced by the degaussing of Allied ships, Dönitz decided to use new contact pistols, which were copied from British torpedoes found in the captured British submarine HMS Seal . The depth setting mechanism was improved but only in January 1942 were the last complications with that mechanism discovered and fixed, making the torpedo a more reliable weapon. The German occupation of Norway in April 1940,
16226-443: Was better protected in one convoy than in two. A large convoy was as difficult to locate as a small one. Moreover, reduced frequency also reduced the chances of detection, as fewer large convoys could carry the same amount of cargo, while large convoys take longer to assemble. Therefore, a few large convoys with apparently few escorts were safer than many small convoys with a higher ratio of escorts to merchantmen. Instead of attacking
16359-419: Was declared in September 1939, including most of the available U-boats and the "pocket battleships" Deutschland and Admiral Graf Spee which had sortied into the Atlantic in August. These ships immediately attacked British and French shipping. U-30 sank the ocean liner SS Athenia within hours of the declaration of war—in breach of her orders not to sink passenger ships. The U-boat fleet, which
16492-435: Was deeply flawed because a U-boat, with its tiny silhouette, was always likely to spot the surface warships and submerge long before it was sighted. The carrier aircraft were little help; although they could spot submarines on the surface, at this stage of the war they had no adequate weapons to attack them, and any submarine found by an aircraft was long gone by the time surface warships arrived. The hunting group strategy proved
16625-463: Was initiated. Merchant ships that were either too fast or too slow for convoys, were to be equipped with a self-defence gun against surfaced submarine attacks, thus forcing an attacking U-boat to spend its precious torpedoes. This, however, removed these ships from the protection of the cruiser rules under the prize law . Nevertheless, despite this lack of readiness, in 1939 the Royal Navy probably had as many ASDIC equipped warships in service as all
16758-452: 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
16891-505: Was referred to by U-boat crews as "the Happy Time" (" Die Glückliche Zeit "). Churchill would later write: "...the only thing that ever frightened me during the war was the U-boat peril". The biggest challenge for the U-boats was to find the convoys in the vastness of the ocean. The Germans had a handful of very long-range Focke-Wulf Fw 200 Condor aircraft based at Bordeaux and Stavanger , which were used for reconnaissance. The Condor
17024-761: 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
17157-546: 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
17290-470: Was surpassed a month later when Günther Prien in U-47 penetrated the British base at Scapa Flow and sank the old battleship HMS Royal Oak at anchor, immediately becoming a hero in Germany. In the South Atlantic, British forces were stretched by the cruise of Admiral Graf Spee , which sank nine merchant ships of 50,000 gross register tons (GRT) in the South Atlantic and Indian Ocean during
17423-547: Was to be many months before these ships contributed to the campaign. The early U-boat operations from the French bases were spectacularly successful. This was the heyday of the great U-boat aces like Günther Prien of U-47 , Otto Kretschmer ( U-99 ), Joachim Schepke ( U-100 ), Engelbert Endrass ( U-46 ), Victor Oehrn ( U-37 ) and Heinrich Bleichrodt ( U-48 ). U-boat crews became heroes in Germany. From June until October 1940, over 270 Allied ships were sunk; this period
17556-403: Was to dominate so much of the Battle of the Atlantic, was small at the beginning of the war; many of the 57 available U-boats were the small and short-range Type IIs , useful primarily for minelaying and operations in British coastal waters. Much of the early German anti-shipping activity involved minelaying by destroyers , aircraft and U-boats off British ports. With the outbreak of war,
17689-416: Was to pass over the submarine, rolling depth charges from chutes at the stern, while throwers fired further charges to either side, laying a pattern of depth charges. To effectively disable a submarine, a depth charge had to explode within about 20 ft (6.1 m). Since early ASDIC equipment was poor at determining depth, it was usual to vary the depth settings on part of the pattern. When in spring 1939
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