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75-623: A bunker is a defensive military fortification designed to protect people and valued materials from falling bombs, artillery, or other attacks. Bunkers are almost always underground, in contrast to blockhouses which are mostly above ground. They were used extensively in World War I , World War II , and the Cold War for weapons facilities, command and control centers, and storage facilities. Bunkers can also be used as protection from tornadoes . Trench bunkers are small concrete structures, partly dug into

150-407: A Scots word for "bench, seat" recorded 1758, alongside shortened bunk "sleeping berth". The word possibly has a Scandinavian origin: Old Swedish bunke means "boards used to protect the cargo of a ship". In the 19th century the word came to describe a coal store in a house, or below decks in a ship. It was also used for a sand-filled depression installed on a golf course as a hazard. In

225-829: A palisade with the blockhouse at one corner, and possibly a second tower at the opposite corner. Many historical stone blockhouses have survived, and a few timber ones have been restored at historical sites. In New Zealand, the Cameron Blockhouse , near Whanganui , is one of the few blockhouses to survive from the New Zealand Wars . During the Second Boer War the British forces built a large number of fortifications in South Africa . Around 441 were solid masonry blockhouses, many of which stand today. Different designs were used in

300-471: A pillbox can be killed with flamethrowers . Complex, well-built and well-protected fortifications are often vulnerable to attacks on access points. If the exits to the surface can be closed off, those manning the facility can be trapped. The fortification can then be bypassed. Famous bunkers include the post-World War I Maginot Line on the French eastern border and Czechoslovak border fortifications mainly on

375-492: A colonial power took over an overseas territory, one of their first tasks was to build a coastal fortress, both to deter rival naval powers and to subjugate the natives. The Martello tower is an excellent example of a widely used coastal fort that mounted defensive artillery, in this case, muzzle-loading cannon. During the 19th century China also built hundreds of coastal fortresses in an attempt to counter Western naval threats. Coastal artillery fortifications generally followed

450-501: A few had semi-circular or rectangular platforms. Surviving redoubts with blockhouses include Baħar iċ-Ċagħaq Redoubt and Briconet Redoubt , both of which have a pentagonal plan. A few of the redoubts consisted of a single tower-like blockhouse without a platform, and were known as tour-reduits . Of the four tour-reduits that were built, only the Vendôme Tower survives today. Originally blockhouses were often constructed as part of

525-421: A house is purpose-built with a bunker, the normal location is a reinforced below-ground bathroom with large cabinets. One common design approach uses fibre-reinforced plastic shells. Compressive protection may be provided by inexpensive earth arching. The overburden is designed to shield from radiation. To prevent the shelter from floating to the surface in high groundwater, some designs have a skirt held down with

600-525: A large plan, to "block" access to vital points in the scheme. But from the Age of Exploration to the nineteenth century standard patterns of blockhouses were constructed for defence in frontier areas, particularly South Africa , New Zealand , Canada , and the United States . Blockhouses may be made of masonry where available, but were commonly made from very heavy timbers , sometimes even logs arranged in

675-589: A modern blockhouse and a bunker is that a bunker is constructed mostly below ground level while a blockhouse is constructed mostly above ground level. Some blockhouses like those constructed in England in 1940 were built in anticipation of a German invasion ; they were often hexagonal in shape and were called " pillboxes ". About 28,000 pillboxes and other hardened field fortifications were constructed, of which about 6,500 still survive. The Admiralty Citadel in London

750-400: A narrow, 1–2-metre (3.5–6.5 ft), flexible tent of thin wood is placed in a deep trench, and then covered with cloth or plastic, and then covered with 1–2 m (3.5–6.5 feet) of tamped earth. A large ground shock can move the walls of a bunker several centimeters in a few milliseconds. Bunkers designed for large ground shocks must have sprung internal buildings to protect inhabitants from

825-416: A protected harbor's defences. In the middle 19th century underwater minefields and later controlled mines were often used, or stored in peacetime to be available in wartime. With the rise of the submarine threat at the beginning of the 20th century, anti-submarine nets were used extensively, usually added to boom defences, with major warships often being equipped with them (to allow rapid deployment once

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900-512: A string of reinforced concrete pillboxes and bunkers along the beaches, or sometimes slightly inland, to house machine guns , antitank guns , and artillery ranging in size up to the large 40.6 cm naval guns . The intent was to destroy Allied landing craft before they could unload. During the Normandy Landings in 1944, shore bombardment was given a high importance, using ships from battleships to destroyers and landing craft. For example,

975-416: Is a small fortification , usually consisting of one or more rooms with loopholes , allowing its defenders to fire in various directions. It is usually an isolated fort in the form of a single building, serving as a defensive strong point against any enemy that does not possess siege equipment or, in modern times, artillery , air force or cruise missiles . A fortification intended to resist these weapons

1050-415: Is an unusually large number of bunkers because of a law requiring protective shelters to be constructed for all new buildings since 1963, as well as a number of bunkers built as part of its National Redoubt military defense plan. Some of Switzerland's bunkers have since become tourist attractions housing hotels and museums such as Sasso San Gottardo Museum. The Soviet Union maintained huge bunkers (one of

1125-412: Is more likely to qualify as a fortress or a redoubt , or in modern times, be an underground bunker . However, a blockhouse may also refer to a room within a larger fortification, usually a battery or redoubt. The term blockhouse is of uncertain origin, perhaps related to Middle Dutch blokhus and 18th-century French blocus (blockade). Blockhouses existed in ancient Greece, for example

1200-651: Is one of the sturdiest above-ground structures built during World War II. It was constructed in 1940–1941 as a bomb-proof operations centre for the Admiralty , with foundations nine metres deep and a concrete roof six metres thick. It too was intended to serve as a strongpoint in defending against the feared invasion. In Berlin and other cities during World War II some massive blockhouses were built as air-raid shelters and anti-aircraft artillery platforms. They were called Hochbunker (literally, "high bunkers"; better translated as "above ground bunkers", to distinguish them from

1275-515: Is recognized as under the nation or state's laws. One of the first recorded uses of coastal artillery was in 1381—during the war between Ferdinand I of Portugal and Henry II of Castile —when the troops of the King of Portugal used cannons to defend Lisbon against an attack from the Castilian naval fleet. The use of coastal artillery expanded during the Age of Discoveries , in the 16th century; when

1350-489: Is the igloo shaped bunker. They are often built into a hillside in order to provide additional containment mass. A specialized version of the munitions bunker called a Gravel Gertie is designed to contain radioactive debris from an explosive accident while assembling or disassembling nuclear warheads . They are installed at all facilities in the United States and United Kingdom which do warhead assembly and disassembly,

1425-742: The East Wing of the White House serves as a secure shelter and communications center for the President of the United States in case of an emergency. 1. abmm.org : Australian Bunker And Military Museum 2. BunkerBlog : All about German fortifications 1933-1945 3. Bunkersite.com : About bunkers built by the Germans during 1933–1945 in the whole of Europe 4. German bunkers in Poland : Fortified Front Odra-Warta rivers, Boryszyn Loop Blockhouse A blockhouse

1500-523: The Endicott Board recommended an extensive program of new U.S. harbor defenses , featuring new rifled artillery and minefield defenses; most of the board's recommendations were implemented. Construction on these was initially slow, as new weapons and systems were developed from scratch, but was greatly hastened following the Spanish–American War of 1898. Shortly thereafter, in 1907, Congress split

1575-765: The Far East the term was also applied to the earth and log positions built by the Japanese, the term appearing in a 1943 instruction manual issued by the British Indian Army and quickly gaining wide currency. By 1947 the word was familiar enough in English that Hugh Trevor-Roper in The Last Days of Hitler was describing Hitler's underground complex near the Reich Chancellery as "Hitler's own bunker" without quotes around

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1650-696: The First World War the belligerents built underground shelters, called dugouts in English , while the Germans used the term Bunker . By the Second World War the term came to be used by the Germans to describe permanent structures both large ( blockhouses ), and small ( pillboxes ), and bombproof shelters both above ground (as in Hochbunker ) and below ground (such as the Führerbunker ). The military sense of

1725-592: The Siege of Port Arthur , Japanese forces had captured the vantage point on 203 Meter Hill overlooking Port Arthur harbor. After relocating heavy 11-inch (280 mm) howitzers with 500 pound (~220 kg) armor-piercing shells to the summit of the Hill, the Japanese bombarded the Russian fleet in the harbor, systematically sinking the Russian ships within range. The Japanese were attacking

1800-630: The Thames Estuary , the Solent , and Plymouth . Often sited in pairs, the blockhouses were not built to a common design, but usually consisted of a stone tower and bastion or gun platform, which could be semi-circular, rectangular or irregular in shape. The last blockhouse of this type was Cromwell's Castle , built in Scilly in 1651. Blockhouses were an ubiquitous feature in Malta 's coastal fortifications built in

1875-553: The 18th century by the Order of St. John . Between 1714 and 1716, dozens of batteries and redoubts were built around the coasts of the Maltese Islands, while a few others were built in the subsequent decades. Almost every battery and redoubt had a blockhouse, which served as gun crew accommodation and a place to store munitions. Many of the batteries consisted of a semi-circular or polygonal gun platform, with one or two blockhouses at

1950-658: The Army (as in English-speaking countries ). In English-speaking countries, certain coastal artillery positions were sometimes referred to as 'Land Batteries', distinguishing this form of artillery battery from for example floating batteries . In the United Kingdom, in the later 19th and earlier 20th Centuries, the land batteries of the coastal artillery were the responsibility of the Royal Garrison Artillery . In

2025-571: The Canadians at Juno beach had fire support many times greater than they had had for the Dieppe Raid in 1942. The old battleships HMS Ramillies and Warspite with the monitor HMS Roberts were used to suppress shore batteries east of the Orne ; cruisers targeted shore batteries at Ver-sur-Mer and Moulineaux ; while eleven destroyers provided local fire support. The (equally old) battleship Texas

2100-561: The German battery. Allied efforts to take the port of Toulon in August 1944 ran into "Big Willie", a battery consisting of two prewar French turrets, equipped with the guns taken from the French battleship Provence , each mounting a pair of 340 mm naval guns . The range and power of these guns was such that the Allies dedicated a battleship or heavy cruiser to shelling the fort every day, with

2175-542: The Japanese had for the coastal artillery at Singapore. However, the lack of HE shells rendered Singapore vulnerable to a land based attack from Malaya via the Johore straits. In December 1941, during the Battle of Wake Island , US Marine defense battalions fired at the Japanese invasion fleet with six 5-inch (127 mm) guns , sinking the Japanese destroyer Hayate by scoring direct hits on her magazines, and scoring eleven hits on

2250-521: The United States, coastal artillery was established in 1794 as a branch of the Army and a series of construction programs of coastal defenses began: the "First System" in 1794, the "Second System" in 1804, and the "Third System" or "Permanent System" in 1816. Masonry forts were determined to be obsolete following the American Civil War, and a postwar program of earthwork defenses was poorly funded. In 1885

2325-418: The battleship Nevada eventually silencing the guns on August 23, 1944. After World War II the advent of jet aircraft and guided missiles reduced the role of coastal artillery in defending a country against air and sea attacks while also rendering fixed artillery emplacements vulnerable to enemy strikes. The Scandinavian countries, with their long coastlines and relatively weak navies, continued in

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2400-542: The blast wave from nearby explosions to prevent ear and internal injuries to people sheltering in the bunker. Nuclear bunkers must also cope with the underpressure that lasts for several seconds after the shock wave passes, and block radiation . A bunker's door must be at least as strong as the walls. In bunkers inhabited for prolonged periods, large amounts of ventilation or air conditioning must be provided. Bunkers can be destroyed with powerful explosives and bunker-busting warheads . The word bunker originates as

2475-452: The blast wave or a reflection cannot lift the edge. A bunker should have two doors. Door shafts may double as ventilation shafts to reduce digging. In bunkers inhabited for prolonged periods, large amounts of ventilation or air conditioning must be provided in order to prevent ill effects of heat. In bunkers designed for war-time use, manually operated ventilators must be provided because supplies of electricity or gas are unreliable. One of

2550-439: The ceiling, with a bench lining the walls inside for defenders to stand on, so that attackers could not easily reach the loopholes. Blockhouses were normally entered via a sturdy, barred door at ground level. Most blockhouses were roughly square in plan , but some of the more elaborate ones were hexagonal or octagonal , to provide better all-around fire. In some cases, blockhouses became the basis for complete forts, by building

2625-512: The city and the Russian ships were trapped in the harbor due to mines, making this one of the few cases of coastal guns being employed in an offensive action. On December 5, 1904, the battleship Poltava was destroyed, followed by the battleship Retvizan on December 7, 1904, the battleships Pobeda and Peresvet and the cruisers Pallada and Bayan on December 9, 1904. The battleship Sevastopol , although hit 5 times by 11-inch (280 mm) shells, managed to move out of range of

2700-572: The construction of these blockhouses, but most were either two or three story structures built using locally quarried stone. However the vast scale of British strategy led the British to develop cheaper, double-skinned corrugated iron structures. These could be prefabricated, delivered to site by armoured train, and then have locally sourced rocks or rubble packed inside the double skin to provide improved protection. A circular design developed by Major Rice in February 1901 had good all round visibility, and

2775-422: The cost to build a blockhouse dropped down to £16, compared to several hundred pounds for masonry ones. These blockhouses played a vital role in the protection of the railway lines and bridges that were key to the British military supply lines. During World War I and World War II , many types of blockhouses were built, when time allowed usually constructed of reinforced concrete . The major difference between

2850-506: The cruiser Takasago to a mine outside the harbor. During the Battle of Drøbak Sound in April 1940, the German navy lost the new heavy cruiser Blücher , one of their most modern ships, to a combination of fire from various coastal artillery emplacements, including two obsolete German-made Krupp 280 mm (11 in) guns and equally obsolete Whitehead torpedoes . The Blücher had entered

2925-596: The development and installation of modern coastal artillery systems, usually hidden in well-camouflaged armored turrets (for example Swedish 12 cm automatic turret gun ). In these countries the coastal artillery was part of the naval forces and used naval targeting systems. Both mobile and stationary (e.g. 100 56 TK ) systems were used. In countries where coastal artillery has not been disbanded, these forces have acquired amphibious or anti-ship missile capabilities. In constricted waters, mobile coastal artillery armed with surface-to-surface missiles still can be used to deny

3000-454: The development of land fortifications; sometimes separate land defence forts were built to protect coastal forts. Through the middle 19th century, coastal forts could be bastion forts , star forts , polygonal forts , or sea forts , the first three types often with detached gun batteries called "water batteries". Coastal defence weapons throughout history were heavy naval guns or weapons based on them, often supplemented by lighter weapons. In

3075-623: The field artillery and coast artillery into separate branches, creating a separate Coast Artillery Corps (CAC) The CAC was disbanded as a separate branch in 1950. In the first decade of the 20th century, the United States Marine Corps established the Advanced Base Force . The force was used for setting up and defending advanced overseas bases, and its close ties to the Navy allowed it to man coast artillery around these bases. During

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3150-524: The fires reached her magazines and doomed her. As a result, the remainder of the invasion fleet reversed, the Norwegian royal family, parliament and cabinet escaped, and the Norwegian gold reserves were safely removed from the city before it fell. Singapore was defended by its famous large-caliber coastal guns, which included one battery of three 15-inch (381 mm) guns and one with two 15-inch (381 mm) guns. Prime Minister Winston Churchill nicknamed

3225-451: The form of cannons were highly important to military affairs and generally represented the areas of highest technology and capital cost among materiel . The advent of 20th-century technologies, especially military aviation , naval aviation , jet aircraft , and guided missiles , reduced the primacy of cannons, battleships, and coastal artillery. It was long held as a rule of thumb that one shore-based gun equaled three naval guns of

3300-609: The garrison as "The Gibraltar of the East" and the "Lion of the Sea". This perhaps compelled the Japanese to launch their invasion of Singapore from the north, via Malaya , in December 1941. It is a commonly repeated misconception that Singapore's large-calibre coastal guns were ineffective against the Japanese because they were designed to face south to defend the harbour against naval attack and could not be turned round to face north. In fact, most of

3375-433: The ground. Many artillery installations, especially for coastal artillery , have historically been protected by extensive bunker systems. Typical industrial bunkers include mining sites, food storage areas, dumps for materials, data storage, and sometimes living quarters. When a house is purpose-built with a bunker, the normal location is a reinforced below-ground bathroom with fiber-reinforced plastic shells. Bunkers deflect

3450-462: The guns could be turned, and were indeed fired at the invaders. However, the guns were supplied mostly with armour-piercing (AP) shells and few high explosive (HE) shells. AP shells were designed to penetrate the hulls of heavily armoured warships and were mostly ineffective against infantry targets. Military analysts later estimated that if the guns had been well supplied with HE shells the Japanese attackers would have suffered heavy casualties, but

3525-710: The guns. Stung by the fact that the Russian Pacific Fleet had been sunk by the army and not by the Imperial Japanese Navy, and with a direct order from Tokyo that the Sevastopol was not to be allowed to escape, Admiral Togo sent in wave after wave of destroyers in six separate attacks on the sole remaining Russian battleship. After 3 weeks, the Sevastopol was still afloat, having survived 124 torpedoes fired at her while sinking two Japanese destroyers and damaging six other vessels. The Japanese had meanwhile lost

3600-539: The inability to use Manila as a port), the forts allowed interception of radio traffic later decisive at Midway. The Japanese defended the island of Betio in the Tarawa atoll with numerous 203 mm (8-inch) coastal guns. In 1943, these were knocked out early in the battle with a combined USN naval and aerial bombardment. Nazi Germany fortified its conquered territories with the Atlantic Wall . Organization Todt built

3675-409: The invasion would not have been prevented by this means alone. The guns of Singapore achieved their purpose in deterring a Japanese naval attack as the possibility of an expensive capital ship being sunk made it inadvisable for the Japanese to attack Singapore via the sea. The very fact that the Japanese chose to advance down from Thailand through Malaya to take Singapore was a testament for the respect

3750-449: The lack of corners did away with the need for a substructure. Failure due to wood rot and splintering when hit by bullets or shrapnel were eliminated. The steel door to the blockhouse was sheltered by another piece of corrugated iron. The Major Rice blockhouse could be erected in six hours by six trained men. With the change from square gabled roofs to a circular design, they were given the nickname "Pepperpot blockhouse". With mass production

3825-553: The largest being the Pantex plant in Amarillo, Texas , which has 12 Gravel Gerties. Bunkers deflect the blast wave from nearby explosions to prevent ear and internal injuries to people sheltering in the bunker. While frame buildings collapse from as little as 21  kPa (3  psi ; 0.21  bar ) of overpressure , bunkers are regularly constructed to survive over 1,000 kPa (150 psi; 10 bar). This substantially decreases

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3900-837: The largest individual pre-Cold War bunkers. The walls of the ' Batterie Todt ' gun installation in northern France were up to 3.5 metres (11 ft) thick, and an underground bunker was constructed for the V-3 cannon . Typical industrial bunkers include mining sites, food storage areas, dumps for materials, data storage, and sometimes living quarters. They were built mainly by nations like Germany during World War II to protect important industries from aerial bombardment . Industrial bunkers are also built for control rooms of dangerous activities, such as tests of rocket engines or explosive experiments. They are also built in order to perform dangerous experiments in them or to store radioactive or explosive goods. Such bunkers also exist on non-military facilities. When

3975-401: The late 19th century separate batteries of coastal artillery replaced forts in some countries; in some areas, these became widely separated geographically through the mid-20th century as weapon ranges increased. The amount of landward defence provided began to vary by country from the late 19th century; by 1900 new US forts almost totally neglected these defences. Booms were also usually part of

4050-404: The light cruiser Yubari , forcing her to withdraw, and temporarily repulsing Japanese efforts to take the island. The Harbor Defenses of Manila and Subic Bays denied Manila harbor to the invading Japanese until Corregidor fell to amphibious assault on 6 May 1942, nearly a month after the fall of Bataan . Beyond tying up besieging Japanese forces (who suffered severe supply shortages due to

4125-513: The likelihood that a bomb (other than a bunker buster ) can harm the structure. The basic plan is to provide a structure that is very strong in physical compression . The most common purpose-built structure is a buried, steel reinforced concrete vault or arch . Most expedient blast shelters are civil engineering structures that contain large, buried tubes or pipes such as sewage or rapid transit tunnels. Improvised purpose-built blast shelters normally use earthen arches or vaults. To form these,

4200-471: The manner of a log cabin . They were usually two or even three floors , with all storeys being provided with embrasures or loopholes, and the uppermost storey would be roofed. If the structure was of timber, usually the upper storey would project outward from the lower so the upper storey defenders could fire on enemies attacking the lower storey, or perhaps pour water on any fires. When the structure had only one storey, its loopholes were often placed close to

4275-503: The most efficient manual ventilator designs is the Kearny Air Pump . Ventilation openings in a bunker must be protected by blast valves . A blast valve is closed by a shock wave, but otherwise remains open. One form of expedient blast valve is worn flat rubber tire treads nailed or bolted to frames strong enough to resist the maximum overpressure. Bunkers can be destroyed with powerful explosives and bunkerbusting warheads. The crew of

4350-465: The muzzle pointing upwards (e.g., mortars and anti-aircraft weapons). Many artillery installations, especially for coastal artillery , have historically been protected by extensive bunker systems. These usually housed the crews serving the weapons, protected the ammunition against counter-battery fire, and in numerous examples also protected the guns themselves, though this was usually a trade-off reducing their fields of fire. Artillery bunkers are some of

4425-506: The narrow waters of the Oslofjord , carrying 1,000 soldiers and leading a German invasion fleet. The first salvo from the Norwegian defenders, fired from Oscarsborg Fortress about 950 meters distance, disabled the center propeller turbine and set her afire. Fire from the smaller guns (57 mm to 150 mm) swept her decks and disabled her steering, and she received two torpedo hits before

4500-907: The northern Czech border facing Germany (but to lesser extent all around), Fort Eben-Emael in Belgium, Alpine Wall on the north of Italy, World War II Führerbunker and in Italy, industrial Marnate's Bunker , the V-weapon installations in Germany ( Mittelwerk ) & France ( La Coupole , and the Blockhaus d'Éperlecques ) and the Cold War installations in the United States ( Cheyenne Mountain Complex , Site R , and The Greenbrier ), United Kingdom ( Burlington ), Sweden ( Boden Fortress ) and Canada ( Diefenbunker ). In Switzerland, there

4575-581: The one near Mycenae . Early blockhouses were designed solely to protect a particular area by the use of artillery, and they had accommodation only for the short-term use of the garrison. The first known example is the Cow Tower, Norwich , built in 1398, which was of brick and had three storeys with the upper storeys pierced for six guns each. The major period of construction was in the maritime defence programmes of Henry VIII between 1539 and 1545. They were built to protect important maritime approaches such as

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4650-494: The overburden. It may also serve the purpose of a safe room . Large bunkers are often bought by super rich individuals in case of political instability , and usually store or access large amounts of energy for use. They are sometimes refereed to as "luxury bunkers," and their locations are often documented. Munitions storage bunkers are designed to securely store explosive ordnance and contain any internal explosions. The most common configuration for high explosives storage

4725-411: The rear. The blockhouses usually had musketry loopholes, and in some cases were linked together by redans . Surviving batteries include Mistra Battery and Ferretti Battery , which both have two blockhouses, and Saint Mary's Battery and Saint Anthony's Battery , which have a single blockhouse. Many of the redoubts consisted of a pentagonal platform with a rectangular blockhouse at the rear, although

4800-578: The run-in to the beach. Similar arrangements existed at other beaches. On June 25, 1944, the American battleship Texas engaged German shore batteries on the Cotentin Peninsula around Cherbourg. Battery Hamburg straddled the ship with a salvo of 240 mm shells, eventually hitting Texas twice; one shell damaging the conning tower and navigation bridge, with the other penetrating below decks but failing to explode. Return fire from Texas knocked out

4875-420: The same caliber, due to the steadiness of the coastal gun which allowed for significantly higher accuracy than their sea-mounted counterparts. Land-based guns also benefited in most cases from the additional protection of walls or earth mounds. The range of gunpowder -based coastal artillery also has a derivative role in international law and diplomacy, wherein a country's three-mile limit of "coastal waters"

4950-632: The secondary uses of the very deeply dug Moscow Metro and Kyiv metro systems was as nuclear shelters). A number of facilities were constructed in China, such as Beijing 's Underground City and Underground Project 131 in Hubei ; in Albania , Enver Hoxha dotted the country with hundreds of thousands of bunkers . In the United States, the Presidential Emergency Operations Center underneath

5025-537: The ship was anchored or moored) through early World War I. In World War I railway artillery emerged and soon became part of coastal artillery in some countries; with railway artillery in coast defence some type of revolving mount had to be provided to allow tracking of fast-moving targets. Coastal artillery could be part of the Navy (as in Scandinavian countries, war-time Germany , and the Soviet Union ), or part of

5100-570: The use of sea lanes. The Type 88 surface-to-ship missile is an example of modern mobile coastal artillery. Poland also retains a coastal missile division armed with the Naval Strike Missile . During the Croatian War of Independence in 1991, coastal artillery operated by Croatian forces played an important role in defending Croatian Adriatic coast from Yugoslav naval and air strikes, especially around Zadar, Šibenik and Split, defeating

5175-461: The usual deep i.e. underground air raid shelters) and those that functioned as anti-aircraft artillery platforms were also called Flak towers . Some were over six stories high; several survive to this day because of the high cost of demolition. The Hochbunker Pallasstraße  [ de ] in Berlin- Schöneberg has a post-war block of flats built over it. During the Cold War the shelter

5250-407: The walls and floors. Nuclear bunkers must also cope with the underpressure that lasts for several seconds after the shock wave passes, and block radiation . Usually, these features are easy to provide. The overburden ( soil ) and structure provide substantial radiation shielding, and the negative pressure is usually only 1 ⁄ 3 of the overpressure. The doors must be at least as strong as

5325-406: The walls. The usual design is now starting to incorporate vault doors . To reduce the weight, the door is normally constructed of steel, with a fitted steel lintel and frame. Very thick wood also serves and is more resistant to heat because it chars rather than melts. If the door is on the surface and will be exposed to the blast wave, the edge of the door is normally counter-sunk in the frame so that

5400-407: The word bunker. This type of bunker is a small concrete structure, partly dug into the ground, which is usually a part of a trench system. Such bunkers give the defending soldiers better protection than the open trench and also include top protection against aerial attack. They also provide shelter against the weather. Some bunkers may have partially open tops to allow weapons to be discharged with

5475-629: The word was imported into English during World War II, at first in reference to specifically German dug-outs; according to the Oxford English Dictionary , the sense of "military dug-out; a reinforced concrete shelter" is first recorded on 13 October 1939, in "A Nazi field gun hidden in a cemented 'bunker' on the Western front". All the early references to its usage in the Oxford English Dictionary are to German fortifications. However, in

5550-624: Was in use as a NATO foodstore. In the guerrilla phase of the Irish Civil War (1922–1923), a network of blockhouses was constructed to protect the railways from guerrilla attacks. Blockhouses and coordinated road systems were used in the encirclement campaigns of Chiang Kai-shek against the Chinese Communist Party . Coastal artillery From the Middle Ages until World War II , coastal artillery and naval artillery in

5625-614: Was used to suppress the battery at Pointe du Hoc , but the guns there had been moved to an inland position, unbeknownst to the Allies. In addition, there were modified landing craft : eight "Landing Craft Gun", each with two 4.7-inch guns; four "Landing Craft Support" with automatic cannon; eight Landing Craft Tank (Rocket) , each with a single salvo of 1,100 5-inch rockets; eight Landing Craft Assault (Hedgerow), each with twenty-four bombs intended to detonate beach mines prematurely. Twenty-four Landing Craft Tank carried Priest self-propelled 105mm howitzers which also fired while they were on

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