Urban warfare is combat conducted in urban areas such as towns and cities. Urban combat is different from combat in the open at both the operational and tactical level. Complicating factors in urban warfare include the presence of civilians and the complexity of the urban terrain. Urban combat operations may be conducted in order to capitalize on the strategic or tactical advantages with which possession or control of a particular urban area gives or to deny these advantages to the enemy. Fighting in urban areas negates the advantages that one side may have over the other in armour, heavy artillery, or air support. Ambushes laid down by small groups of soldiers with handheld anti-tank weapons can destroy entire columns of modern armour, while artillery and air support can be reduced if the'superior' party wants to limit civilian casualties as much as possible, but the defending party does not; some civilians may be difficult to distinguish from combatants such as armed militias and gangs, individuals who are trying to protect their homes from attackers.
Tactics are complicated by a three-dimensional environment, limited fields of view and fire because of buildings, enhanced concealment and cover for defenders, below-ground infrastructure, the ease of placement of booby traps and snipers. The United States Armed Forces term for urban warfare is an abbreviation for urban operations; the used U. S. military term MOUT, an abbreviation for military operations in urban terrain, has been replaced by UO, although the term MOUT Site is still in use. The British armed forces terms are OBUA, FIBUA, or sometimes FISH, or FISH and CHIPS; the term FOFO refers to clearing enemy personnel from narrow and entrenched places like bunkers and strongholds. Israel Defense Forces calls urban warfare לש "a Hebrew acronym for warfare on urban terrain. LASHAB in the IDF includes CQB training for fighting forces. IDF's LASHAB was developed in recent decades, after the 1982 Lebanon War included urban warfare in Beirut and Lebanese villages, was further developed during the Second Intifada in which IDF soldiers entered and fought in Palestinian cities and refugee camps.
The IDF has a special advanced facility for training soldiers and units in urban warfare. Urban military operations in World War II relied on large quantities of artillery bombardment and air support varying from ground attack fighters to heavy bombers. In some vicious urban warfare operations such as Stalingrad and Warsaw, all weapons were used irrespective of their consequences. However, when liberating occupied territory some restraint was applied in urban settings. For example, Canadian operations in both Ortona and Groningen avoided the use of artillery altogether to spare civilians and buildings, during the Battle of Manila in 1945, General MacArthur placed a ban on artillery and air strikes to save civilian lives. Military forces are bound by the laws of war governing military necessity to the amount of force which can be applied when attacking an area where there are known to be civilians; until the 1970s, this was covered by the 1907 Hague Convention IV – The Laws and Customs of War on Land which includes articles 25–27.
This has since been supplemented by the Additional Protocols to the Geneva Conventions of 12 August 1949, relating to the Protection of Victims of International and Non-International Armed Conflicts. Sometimes distinction and proportionality, as in the case of the Canadians in Ortona, causes the attacking force to restrain from using all the force they could when attacking a city. In other cases, such as the Battle of Stalingrad and the Battle of Berlin, both military forces considered evacuating civilians only to find it impractical; when Russian forces attacked Grozny in 1999, large amounts of artillery fire were used. The Russian Army handled the issue of civilian casualties by warning the inhabitants that they were going to launch an all-out assault on Grozny and requested that all civilians leave the city before the start of the artillery bombardment. Fighting in an urban environment can offer some advantages to a weaker defending force or to guerrilla fighters through ambush-induced attrition losses.
The attacking army must account for three dimensions more and expend greater amounts of manpower in order to secure a myriad of structures, mountains of rubble. Ferroconcrete structures will be ruined by heavy bombardment, but it is difficult to demolish such a building when it is well defended. Soviet forces had to fight room by room, it is difficult to destroy underground or fortified structures such as bunkers and utility tunnels. The characteristics of an average city include tall buildings, narrow alleys, sewage tunnels and a subway system
Hotchkiss M1929 machine gun
The 13.2 mm Hotchkiss machine gun was a heavy machine gun designed and manufactured by Hotchkiss et Cie from the late 1920s until World War II and saw service with various nations' forces, including Italy and Japan where the gun was built under license. In the late 1920s, Hotchkiss proposed a range of anti-aircraft automatic weapons in the 13.2, 25 and 37 mm calibers. They were all based on the same type of gas-operated action; the 8 mm mle 1914 machine gun had proven reliable during World War I and was still in service. The gun started with a 13.2 x 99 cartridge but in 1935 changed over to a 13.2 x 96 cartridge. The majority of guns were fed from overhead 30 round curved box magazines; the guns had a cyclic rate of fire of 450 rounds per minute but their sustained rate of fire was 200-250 rounds per minute due to the need to change magazines which limited their rate of fire. The guns came in a number of different configurations depending on their intended role. There were single and quadruple barreled anti-aircraft weapons on a high-angle pedestal and tripod mounts as well as low-angle bi-pod mounts for anti-tank and heavy machine gun roles.
French infantry commanders that had expressed interest in acquiring light anti-aircraft guns refused to accept the 13.2 mm. They argued that those heavy bullets falling down could be dangerous to friendly troops, went to larger calibers where self-destructing shells were available, but the 13.2 mm Hotchkiss saw extensive use as a naval gun and was chosen by the French cavalry for some of its armored vehicles. The French Air Force used designated as mitrailleuse de 13.2 mm CA mle 1930, for close-range defense of its airfields and other strategic places. It came in two versions: The first was a single gun with a stock and pistol grip that came in a dual-purpose anti-aircraft/anti-armor mounting, it had a two-wheeled split-trailed carriage that weighed 117 kg empty and 155 kg with the machine-gun mounted. When the swing-arm the gun was affixed to was locked upwards, it could be used in an anti-aircraft mode; when the arm was collapsed and a bipod extended it could fire straight ahead in an anti-tank role.
When the gun was packed up and the trails closed, it was towed behind its caisson, pulled by a horse or by the gunner. Second was a fixed tripod mount with a seat and anti-aircraft sight for the gunner, it came in a single mount 120 kg empty, 160 kg mounted. Or a double mount 225 kg empty, 300 kg mounted. Early in World War II, the French and Japanese navies were using twin and quadruple mountings on many of their warships. French warships that were refitted in the United States in 1943, such as the battleship Richelieu or the destroyer Le Terrible, had their 13.2 mm machine guns replaced by more powerful Oerlikon 20 mm cannons. In Italy, the Società Italiana Ernesto Breda produced the gun under license as the Breda Mod.31 from 1931 onwards. It was used as an anti-aircraft gun aboard ships and armored trains Royal Italian Navy. After World War II it was used on the patrol boats of the Guardia di Finanza naval service; the Spanish Navy used it during the Civil War. The "Pirotecnia Militar" Army Ammunition plant produced its cartridges after 1939.
Several self-propelled anti-aircraft combinations were tested in the 1930s, with Citroën-Kegresse or Berliet chassis, but none was mass-manufactured. The 13.2 mm Hotchkiss was used on the Belgian T15 and the French AMR 35, light tanks as well as the AMD Laffly 80 AM armored car and on fortifications. The Free French used field-modified self-propelled mountings, with guns recovered from French ships, in North-East Africa in 1942; the Breda Mod.31 was used as an anti-aircraft and heavy machine gun on command tanks of the Royal Italian Army as well as on L3/33 light tanks sold to Brazil. The Japanese mounted license-produced version of the gun on a number of Type 92 Heavy armored Cars, armed with only a pair of 6.5mm machine guns. Belgium Brazil France Nazi Germany - Captured French guns were designated MG 271. Greece Israel Italy - Built under license as the Breda Model 1931 machine gun. Japan - Built under license as the Type 93 machine gun. Poland - Designated the wz.30. Republic of China Romania - 200 delivered before the Fall of France.
Spain Kingdom of Yugoslavia Anti-aircraft 25 mm Hotchkiss anti-aircraft gun - A related French anti-aircraft gun. Type 96 25 mm AT/AA Gun - A related Japanese anti-aircraft gun. Ferrard, Stéphane. France 1940 l'armement terrestre, ETAI, 1998, ISBN 978-2-7268-8380-8 "Las armas de la guerra civil española", José MAría MANRIQUE, ISBN 84-9734-475-8, pages 394 -398
25 mm Hotchkiss anti-aircraft gun
The Hotchkiss 25 mm anti-aircraft gun was an anti-aircraft autocannon designed by the French firm of Hotchkiss. It served in World War II with French and other nations' forces. Other than the designer company and the calibre, this weapon is not related to the semi-automatic 25 mm Hotchkiss anti-tank gun, in particular, the cartridge used is different. After World War I the French military expressed a need for an anti-aircraft autocannon; the Hotchkiss company submitted its 25 mm design, but it was rejected as being too slow-firing, so the weapon was proposed for export instead. In 1938, as the international situation was worsening, the favoured Schneider 37 mm autocannon was still not ready for production, the French military decided to reconsider its refusal to Hotchkiss, who had just won a contract with Romania; the export guns were impressed into domestic service. The original tripod was found to be unstable, which led to the development of a revised variant with a triangular base with a two-wheel carriage.
This new variant was chosen for mass production, but at the time of the German attack in May 1940, only a few hundred of these guns were in service. With them and only two hundred Oerlikons, the lack of modern light AA guns hampered the French army in the campaign. Romania ordered. Japan bought a licence to manufacture the weapon, which became the Type 96 and was used on most Japanese warships of World War II as the Type 96 25 mm AT/AA Gun; the Spanish Republic bought the weapons for its Navy in December 1935. Five were received in January 1936 and installed during the Spanish Civil War in the destroyers Jose Luis Díez, Lepanto and Ulloa. After the Civil War, these weapons were used during the 1940s. Mitrailleuse de 25 mm contre-aéroplanes modèle 1938 the original tripod-mounted gun intended for Romania.mitrailleuse de 25 mm contre-aéroplanes modèle 1939 heavier, more stable carriage.mitrailleuse de 25 mm contre-aéroplanes modèle 1940 faster-firing variant on fixed mounting for naval and static defense use, cartwheel sights.mitrailleuse de 25 mm contre-aéroplanes modèle 1940 jumelée ground-based twin variant.
13.2 mm Hotchkiss machine gun, a related weapon Ferrard, Stéphane. France 1940 l'armement terrestre, ETAI, 1998, ISBN 978-2-7268-8380-8 Notice provisoire du matériel de 25 m/m C. A. Modèle 1938, Manufacture d'armes de Levallois, 1939 Rapid fire, Anthony G. Williams, ISBN 1-84037-435-7 "Las armas de la guerra civil española", José María Manrique, ISBN 84-9734-475-8, pages 394 -398 Munitions de 25 mm Hotchkiss Modèle 1938
World War I
World War I known as the First World War or the Great War, was a global war originating in Europe that lasted from 28 July 1914 to 11 November 1918. Contemporaneously described as "the war to end all wars", it led to the mobilisation of more than 70 million military personnel, including 60 million Europeans, making it one of the largest wars in history, it is one of the deadliest conflicts in history, with an estimated nine million combatants and seven million civilian deaths as a direct result of the war, while resulting genocides and the 1918 influenza pandemic caused another 50 to 100 million deaths worldwide. On 28 June 1914, Gavrilo Princip, a Bosnian Serb Yugoslav nationalist, assassinated the Austro-Hungarian heir Archduke Franz Ferdinand in Sarajevo, leading to the July Crisis. In response, on 23 July Austria-Hungary issued an ultimatum to Serbia. Serbia's reply failed to satisfy the Austrians, the two moved to a war footing. A network of interlocking alliances enlarged the crisis from a bilateral issue in the Balkans to one involving most of Europe.
By July 1914, the great powers of Europe were divided into two coalitions: the Triple Entente—consisting of France and Britain—and the Triple Alliance of Germany, Austria-Hungary and Italy. Russia felt it necessary to back Serbia and, after Austria-Hungary shelled the Serbian capital of Belgrade on the 28th, partial mobilisation was approved. General Russian mobilisation was announced on the evening of 30 July; when Russia failed to comply, Germany declared war on 1 August in support of Austria-Hungary, with Austria-Hungary following suit on 6th. German strategy for a war on two fronts against France and Russia was to concentrate the bulk of its army in the West to defeat France within four weeks shift forces to the East before Russia could mobilise. On 2 August, Germany demanded free passage through Belgium, an essential element in achieving a quick victory over France; when this was refused, German forces invaded Belgium on 3 August and declared war on France the same day. On 12 August and France declared war on Austria-Hungary.
In November 1914, the Ottoman Empire entered the war on the side of the Alliance, opening fronts in the Caucasus and the Sinai Peninsula. The war was fought in and drew upon each power's colonial empire as well, spreading the conflict to Africa and across the globe; the Entente and its allies would become known as the Allied Powers, while the grouping of Austria-Hungary and their allies would become known as the Central Powers. The German advance into France was halted at the Battle of the Marne and by the end of 1914, the Western Front settled into a battle of attrition, marked by a long series of trench lines that changed little until 1917. In 1915, Italy opened a front in the Alps. Bulgaria joined the Central Powers in 1915 and Greece joined the Allies in 1917, expanding the war in the Balkans; the United States remained neutral, although by doing nothing to prevent the Allies from procuring American supplies whilst the Allied blockade prevented the Germans from doing the same the U. S. became an important supplier of war material to the Allies.
After the sinking of American merchant ships by German submarines, the revelation that the Germans were trying to incite Mexico to make war on the United States, the U. S. declared war on Germany on 6 April 1917. Trained American forces would not begin arriving at the front in large numbers until mid-1918, but the American Expeditionary Force would reach some two million troops. Though Serbia was defeated in 1915, Romania joined the Allied Powers in 1916 only to be defeated in 1917, none of the great powers were knocked out of the war until 1918; the 1917 February Revolution in Russia replaced the Tsarist autocracy with the Provisional Government, but continuing discontent at the cost of the war led to the October Revolution, the creation of the Soviet Socialist Republic, the signing of the Treaty of Brest-Litovsk by the new government in March 1918, ending Russia's involvement in the war. This allowed the transfer of large numbers of German troops from the East to the Western Front, resulting in the German March 1918 Offensive.
This offensive was successful, but the Allies rallied and drove the Germans back in their Hundred Days Offensive. Bulgaria was the first Central Power to sign an armistice—the Armistice of Salonica on 29 September 1918. On 30 October, the Ottoman Empire capitulated. On 4 November, the Austro-Hungarian empire agreed to the Armistice of Villa Giusti after being decisively defeated by Italy in the Battle of Vittorio Veneto. With its allies defeated, revolution at home, the military no longer willing to fight, Kaiser Wilhelm abdicated on 9 November and Germany signed an armistice on 11 November 1918. World War I was a significant turning point in the political, cultural and social climate of the world; the war and its immediate aftermath sparked numerous uprisings. The Big Four (Britain, the United States, It
Hotchkiss M1909 Benét–Mercié machine gun
The Hotchkiss M1909 machine gun was a light machine gun of the early 20th century and built by Hotchkiss et Cie. It was known as the Hotchkiss Mark I, Hotchkiss Portative and M1909 Benét–Mercié, it was based on a design by Austrian nobleman and Army officer, Adolf Odkolek von Újezd, who sold the manufacturing rights to Hotchkiss in 1893. Several improved versions were designed by Hotchkiss's American manager, Laurence Benét and his French assistant, Henri Mercié, it had a maximum range of 3,800 m and weighed 12 kg. Initial models were fed by a 30-round feed strip but models could be either strip-fed or belt-fed; the U. S. types had a bipod. This tripod, fitted under the firearm, could be moved with the weapon, was different from larger tripods of the period. Production began at the Hotchkiss factory in Saint-Denis, but in 1914, with the invading German army threatening the city, the French military authorities ordered the factory to be moved to Lyon; the following year, the British government invited Hotchkiss to set up a factory in Coventry.
By the end of the war, this factory had manufactured over 40,000 M1909s. The U. S. version was made by Colt's Manufacturing Company. Total production for the United States was 670; this may seem small compared to the huge production runs of firearms in the 20th century, but this was a significant number for the size of the contemporary U. S. Army; the M1909's adoption coincided with the withdrawal of the.30-06 manually operated Gatling guns from the U. S. Army's arsenals; as the Hotchkiss M1909, firing the 8 mm Lebel, it was adopted by the French military in 1909 but not issued as an infantry weapon. The 700 examples manufactured were used in the fortresses at Verdun in a defensive capacity, on some fighter aircraft, in Mark V* tanks acquired from Great Britain. A variant to use the.303 round was produced in Britain at the Coventry factory as the "Hotchkiss Mark I" and issued to some cavalry regiments. The MkI* variant, with the wooden stock replaced with a pistol grip, was used in British tanks during World War I.
It was adopted by the United States in 1909 as the "Benét–Mercié Machine Rifle, Caliber.30 U. S. Model of 1909" firing the.30-06 cartridge. It was used by other countries, including Belgium and Mexico. France and Britain used the Hotchkiss M1909 through World War I and on into World War II; the Australian Light Horse, the New Zealand Mounted Rifles Brigade, the Imperial Camel Corps, the Duke of Lancaster's Own Yeomanry used the Hotchkiss in the Sinai and Palestine Campaign. U. S. forces used the Benét–Mercié at the Battle of Columbus in 1916, in the subsequent Pancho Villa Expedition in Mexico of 1916–17, in France. On the American guns, firing pins and extractors broke frequently; some members of the U. S. press derisively called the M1909 the "daylight gun" because of the difficulty in replacing broken parts at night and jams caused when a loading strip was inserted upside down in darkness. Major Julian Hatcher was assigned to look into the issue after Columbus and found all the issues were due to inadequate training.
U. S. troops during the Villa Expedition received additional training and the M1909 was considered an effective weapon. During US Service in the Villa Expedition the 1909 was fitted with the Model 1908 Warner & Swasey Musket Sight to aid in long-range firing. U. S. production had ceased before World War I and only a small number were available to the U. S. military. The U. S. Navy still used them, however in that period. Austria-Hungary Australia Belgium Brazil Republic of China Finland France Kingdom of Greece India Ireland: Used in armored cars by the Irish National Army during the Irish Civil War Kingdom of Italy Mexico Russia Spain Sweden United Kingdom United States New Zealand Light machine gun List of individual weapons of the U. S. Armed Forces Huot automatic rifle Chauchat - Another French light machine gun, used by the U. S. Army Hotchkiss M1922 machine gun Segel, Robert G.. "U. S. Automatic Machine Rifle Model of 1909". Small Arms Defense Journal. Vol. 2 no. 4. Images from the Museum of the Soldier, Indiana More images: 1, 2 Complete Guide to the Hotchkiss Machine Gun origyear=1917 http://www.forgottenweapons.com/light-machine-guns/hotchkiss-portative-lmg/ Handbook of the Automatic Machine Rifle Caliber.30, Model of 1909.
Ordnance Department. 31 July 1916. "New Machine Guns Ordered: Vickers Recoil Type Will Replace Those That Jammed". New York Times. 24 March 1916. Collection of photos that appear to be either U. S. Army photos or published before 1922 http://img.photobucket.com/albums/v146/Ordnanceguy/US%20MGs/MGtroopSoldier.jpg http://img.photobucket.com/albums/v146/Ordnanceguy/US%20MGs/BenetMercierRPPC.jpg http://img.photobucket.com/albums/v146/Ordnanceguy/US%20MGs/MoreMGTroopsonBorder1914.jpg http://img.photobucket.com/albums/v146/Ordnanceguy/US%20MGs/MotorcycleMGTroop.jpg http://img.photobucket.com/albums/v146/Ordnanceguy/US%20MGs/M1909BMMGMotorcycleMountedRPPC.jpg http://img.photobucket.com/albums/v146/Ordnanceguy/US%20MGs/BenetMercierMGPlatoon27thInf19131.jpg http://img.photobucket.com/albums/v146/Ordnanceguy/US%20MGs/BenetMercieGroup.jpg
Paris is the capital and most populous city of France, with an area of 105 square kilometres and an official estimated population of 2,140,526 residents as of 1 January 2019. Since the 17th century, Paris has been one of Europe's major centres of finance, commerce, fashion and the arts; the City of Paris is the centre and seat of government of the Île-de-France, or Paris Region, which has an estimated official 2019 population of 12,213,364, or about 18 percent of the population of France. The Paris Region had a GDP of €681 billion in 2016, accounting for 31 percent of the GDP of France, was the 5th largest region by GDP in the world. According to the Economist Intelligence Unit Worldwide Cost of Living Survey in 2018, Paris was the second most expensive city in the world, after Singapore, ahead of Zurich, Hong Kong and Geneva. Another source ranked Paris as most expensive, on a par with Singapore and Hong-Kong, in 2018; the city is a major rail and air-transport hub served by two international airports: Paris-Charles de Gaulle and Paris-Orly.
Opened in 1900, the city's subway system, the Paris Métro, serves 5.23 million passengers daily, is the second busiest metro system in Europe after Moscow Metro. Gare du Nord is the 24th busiest railway station in the world, the first located outside Japan, with 262 million passengers in 2015. Paris is known for its museums and architectural landmarks: the Louvre was the most visited art museum in the world in 2018, with 10.2 million visitors. The Musée d'Orsay and Musée de l'Orangerie are noted for their collections of French Impressionist art, the Pompidou Centre Musée National d'Art Moderne has the largest collection of modern and contemporary art in Europe; the historical district along the Seine in the city centre is classified as a UNESCO Heritage Site. Popular landmarks in the centre of the city include the Cathedral of Notre Dame de Paris and the Gothic royal chapel of Sainte-Chapelle, both on the Île de la Cité. Paris received 23 million visitors in 2017, measured by hotel stays, with the largest numbers of foreign visitors coming from the United States, the UK, Germany and China.
It was ranked as the third most visited travel destination in the world in 2017, after Bangkok and London. The football club Paris Saint-Germain and the rugby union club Stade Français are based in Paris; the 80,000-seat Stade de France, built for the 1998 FIFA World Cup, is located just north of Paris in the neighbouring commune of Saint-Denis. Paris hosts the annual French Open Grand Slam tennis tournament on the red clay of Roland Garros. Paris will host the 2024 Summer Olympics; the 1938 and 1998 FIFA World Cups, the 2007 Rugby World Cup, the 1960, 1984, 2016 UEFA European Championships were held in the city and, every July, the Tour de France bicycle race finishes there. The name "Paris" is derived from the Celtic Parisii tribe; the city's name is not related to the Paris of Greek mythology. Paris is referred to as the City of Light, both because of its leading role during the Age of Enlightenment and more because Paris was one of the first large European cities to use gas street lighting on a grand scale on its boulevards and monuments.
Gas lights were installed on the Place du Carousel, Rue de Rivoli and Place Vendome in 1829. By 1857, the Grand boulevards were lit. By the 1860s, the boulevards and streets of Paris were illuminated by 56,000 gas lamps. Since the late 19th century, Paris has been known as Panam in French slang. Inhabitants are known in French as Parisiens, they are pejoratively called Parigots. The Parisii, a sub-tribe of the Celtic Senones, inhabited the Paris area from around the middle of the 3rd century BC. One of the area's major north–south trade routes crossed the Seine on the île de la Cité; the Parisii minted their own coins for that purpose. The Romans began their settlement on Paris' Left Bank; the Roman town was called Lutetia. It became a prosperous city with a forum, temples, an amphitheatre. By the end of the Western Roman Empire, the town was known as Parisius, a Latin name that would become Paris in French. Christianity was introduced in the middle of the 3rd century AD by Saint Denis, the first Bishop of Paris: according to legend, when he refused to renounce his faith before the Roman occupiers, he was beheaded on the hill which became known as Mons Martyrum "Montmartre", from where he walked headless to the north of the city.
Clovis the Frank, the first king of the Merovingian dynasty, made the city his capital from 508. As the Frankish domination of Gaul began, there was a gradual immigration by the Franks to Paris and the Parisian Francien dialects were born. Fortification of the Île-de-la-Citie failed to avert sacking by Vikings in 845, but Paris' strategic importance—with its bridges prevent
An autocannon or automatic cannon is a large automatic, rapid-fire projectile weapon that fires armour-piercing or explosive shells, as opposed to the bullet fired by a machine gun. Autocannons have a larger calibre than a machine gun, but are smaller than a field gun or other artillery; when used on its own, the word "autocannon" indicates a single-barrel weapon. When multiple rotating barrels are involved, the word "rotary" is added, such a weapon is referred to as a "rotary autocannon". Modern autocannons are not single soldier-portable or stand-alone units, rather they are vehicle-mounted, aircraft-mounted, or boat-mounted, or remote-operated as in some naval applications; as such, ammunition is fed from a belt to reduce reloading or for a faster rate of fire, but a magazine remains an option. They can use a variety of ammunition: common shells include high-explosive dual-purpose types, any variety of armour-piercing types, such as composite rigid or discarding sabot types. Although capable of generating a high rate of fire, autocannons overheat if used for sustained fire, are limited by the amount of ammunition that can be carried by the weapons systems mounting them.
Both the US 25 mm Bushmaster and the British 30 mm Rarden have slow rates of fire so as not to use ammunition too quickly. The rate of fire of a modern autocannon ranges from 90 rounds per minute, to 2,500 rounds per minute with the GIAT 30. Systems with multiple barrels can have rates of fire of over 10,000 rounds per minute; such high rates of fire are employed by aircraft in air-to-air combat and close air support attacks on ground targets, where the target dwell time is short and weapons are operated in brief bursts. The first modern autocannon was the British QF 1 pounder known as the "pom-pom"; this was an upscaled version of the Maxim gun, the first successful automatic machine gun, requiring no outside stimulus in its firing cycle other than holding the trigger. The pom-pom fired 1 pound gunpowder-filled explosive shells at a rate of over 200 rounds a minute: much faster than conventional artillery while possessing a much longer range and more firepower than the infantry rifle. In 1913, Reinhold Becker and his Stahlwerke Becker firm designed the 20mm Becker cannon for the German Empire's perceived need for heavy-calibre aircraft armament, was assisted by the Imperial Government's Spandau Arsenal in perfecting the ordnance - although only about 500+ examples of the original Becker design were made during World War I, the design's patent was acquired by the Swiss Oerlikon Contraves firm in 1924, with the Third Reich's Ikaria-Werke firm of Berlin using Oerlikon design patents in creating the MG FF wingmount cannon ordnance, in Imperial Japan, their navy's adoption and production of the Type 99 cannon in 1939 was based on the Becker/Oerlikon design's principles.
During the First World War, autocannons were used in the trenches as an anti-aircraft gun. The British used pom-pom guns as part of their air defences to counter the German Zeppelin airships that made regular bombing raids on London, but they were of little value, as their shells neither ignited the hydrogen of the Zeppelins, nor caused sufficient loss of gas to bring them down. Attempts to use them in aircraft failed as the weight limited both speed and altitude, thus making successful interception impossible; the more effective QF 2 pounder naval gun would be developed during the war to serve as an anti-aircraft and close range defensive weapon for naval vessels. Autocannons would serve in a much greater capacity during the Second World War. During the inter-war years, aircraft underwent an evolution and the all-metal monoplane, pioneered as far back as the end of 1915 replaced wood and fabric biplanes; the subsequent increase in speed and durability reduced the window of opportunity for defence.
Heavier anti-aircraft cannon had difficulty tracking fast-moving aircraft and were unable to judge altitude or distance, while machine guns possessed insufficient range and firepower to bring down aircraft consistently. Weapons such as the Oerlikon 20 mm and the Bofors 40 mm would see widespread use by both sides during the second World War. Continued ineffectiveness against aircraft despite the large numbers installed during the second World War led, in the West, to the removal of all shipboard anti-aircraft weapons in the early post-war period; this was only reversed with the introduction of computer-controlled systems. The German Panzer II light tank, one of the most numerous in German service during the invasion of Poland and the campaign in France, used a 20 mm autocannon as its main armament. Although ineffective against tank armour during the early years of the war, the cannon was effective against light-skinned vehicles as well as infantry and was used by armoured cars. Larger examples, such as the 40 mm Vickers S, were mounted in ground attack aircraft to serve as an anti-tank weapon, a role to which they were suited as tank armour is lightest on top.
Polish 20 mm. Unlike the Oerlikon, it was effective against all the tanks fielded in 1939 because it was built as an upgrade to the Oerlikon, Hispano—Suiza, Madsen. It, with great difficulty, proved capable of knocking out early Panzer IIIs and IVs. Only 55 were produced by the time of the Polish Defensive War. In airc