Okinawa Prefecture is the southernmost prefecture of Japan. It encompasses two thirds of the Ryukyu Islands in a chain over 1,000 kilometres long; the Ryukyu Islands extend southwest from Kagoshima Prefecture in Kyushu to Taiwan. Naha, Okinawa's capital, is located in the southern part of Okinawa Island. Although Okinawa Prefecture comprises just 0.6 percent of Japan's total land mass, about 75 percent of all United States military personnel stationed in Japan are assigned to installations in the prefecture. About 26,000 U. S. troops are based in the prefecture. The oldest evidence of human existence on the Ryukyu islands is from the Stone Age and was discovered in Naha and Yaeyama; some human bone fragments from the Paleolithic era were unearthed from a site in Naha, but the artifact was lost in transportation before it was examined to be Paleolithic or not. Japanese Jōmon influences are dominant on the Okinawa Islands, although clay vessels on the Sakishima Islands have a commonality with those in Taiwan.
The first mention of the word Ryukyu was written in the Book of Sui. Okinawa was the Japanese word identifying the islands, first seen in the biography of Jianzhen, written in 779. Agricultural societies begun in the 8th century developed until the 12th century. Since the islands are located at the eastern perimeter of the East China Sea close to Japan and South-East Asia, the Ryukyu Kingdom became a prosperous trading nation. During this period, many Gusukus, similar to castles, were constructed; the Ryukyu Kingdom entered into the Imperial Chinese tributary system under the Ming dynasty beginning in the 15th century, which established economic relations between the two nations. In 1609, the Shimazu clan, which controlled the region, now Kagoshima Prefecture, invaded the Ryukyu Kingdom; the Ryukyu Kingdom was obliged to agree to form a suzerain-vassal relationship with the Satsuma and the Tokugawa shogunate, while maintaining its previous role within the Chinese tributary system. The Satsuma clan earned considerable profits from trade with China during a period in which foreign trade was restricted by the shogunate.
Although Satsuma maintained strong influence over the islands, the Ryukyu Kingdom maintained a considerable degree of domestic political freedom for over two hundred years. Four years after the 1868 Meiji Restoration, the Japanese government, through military incursions annexed the kingdom and renamed it Ryukyu han. At the time, the Qing Empire asserted a nominal suzerainty over the islands of the Ryukyu Kingdom, since the Ryūkyū Kingdom was a member state of the Chinese tributary system. Ryukyu han became Okinawa Prefecture of Japan in 1879 though all other hans had become prefectures of Japan in 1872. In 1912, Okinawans first obtained the right to vote for representatives to the National Diet, established in 1890. Near the end of World War II, in 1945, the US Army and Marine Corps invaded Okinawa with 185,000 troops. A third of the civilian population died; the dead, of all nationalities, are commemorated at the Cornerstone of Peace. After the end of World War II, the Ryukyu independence movement developed, while Okinawa was under United States Military Government of the Ryukyu Islands administration for 27 years.
During this "trusteeship rule", the United States established numerous military bases on the Ryukyu islands. During the Korean War, B-29 Superfortresses flew bombing missions over Korea from Kadena Air Base on Okinawa; the military buildup on the island during the Cold War increased a division between local inhabitants and the American military. Under the 1952 Treaty of Mutual Cooperation and Security between the United States and Japan, the United States Forces Japan have maintained a large military presence. Since 1960, the U. S. and Japan have maintained an agreement that allows the U. S. to secretly bring nuclear weapons into Japanese ports. The Japanese tended to oppose the introduction of nuclear arms into Japanese territory by the government's assertion of Japan's non-nuclear policy and a statement of the Three Non-Nuclear Principles. Most of the weapons were alleged to be stored in ammunition bunkers at Kadena Air Base. Between 1954 and 1972, 19 different types of nuclear weapons were deployed in Okinawa, but with fewer than around 1,000 warheads at any one time.
Between 1965 and 1972, Okinawa was a key staging point for the United States in its military operations directed towards North Vietnam. Along with Guam, it presented a geographically strategic launch pad for covert bombing missions over Cambodia and Laos. Anti-Vietnam War sentiment became linked politically to the movement for reversion of Okinawa to Japan. In 1965, the US military bases, earlier viewed as paternal post war protection, were seen as aggressive; the Vietnam War highlighted the differences between the United States and Okinawa, but showed a commonality between the islands and mainland Japan. As controversy grew regarding the alleged placement of nuclear weapons on Okinawa, fears intensified over the escalation of the Vietnam War. Okinawa was perceived, by some inside Japan, as a potential target for China, should the communist government feel threatened by the United States. American military secrecy blocked any local reporting on what was occurring at bases such as Kadena Air Base.
As information leaked out, images of air strikes were published, the local population began to fear the potential for retaliation. Political leaders such as Oda Makoto
Chuuk Lagoon previously known as Truk Lagoon, is a sheltered body of water in the central Pacific. About 1,800 kilometres north-east of New Guinea, it is located mid-ocean at 7 degrees North latitude, is part of Chuuk State within the Federated States of Micronesia; the atoll consists of a protective reef, 225 kilometres around, enclosing a natural harbour 79 by 50 kilometres, with an area of 2,130 square kilometres. It has a land area of 93.07 square kilometres, with a population of 36,158 people and a maximal height of 443 m. Weno city on Moen Island functions as the atoll's capital and as the state capital and is the largest city in the FSM with its 13,700 people. Chuuk means mountain in the Chuukese language; the lagoon was known as Truk, until 1990. Other names included Ruk, Torres and Lugulus. Chuuk Lagoon is part of the larger Caroline Islands group; the area consists of eleven major islands and forty-six smaller ones within the lagoon, plus forty-one on the fringing coral reef, is known today as the Chuuk islands, part of the Federated States of Micronesia in the Pacific Ocean.
This is the following list of islands and population following the 2010 census: It is not known when the islands of Chuuk were first settled, but archaeological evidence indicates that islands of Feefen and Wééné Islands had human settlements in the first and second century BC. Evidence indicates that widespread human settlements appeared in Chuuk during the 14th century AD; the first recorded sighting by Europeans was made by Spanish navigator Álvaro de Saavedra on board of the ship Florida during August or September 1528. They were visited by Spaniard Alonso de Arellano on 15 January 1565 on board of galleon patache San Lucas; as part of the Caroline Islands, Truk was claimed by the Spanish Empire, which made an effort to control the islands in the late 19th century. Chuuk lagoon was inhabited by several tribes that engaged in intermittent warfare, as well as a small population of foreign traders and missionaries. Spanish control over the islands was nominal; the Spaniards stopped to raise a flag over Chuuk in 1886, returned in 1895 as part of an attempt to assert control and negotiate peace between warring Chuukese tribes.
No permanent Spanish settlement was established, tribal violence continued until the German colonial era. The Caroline Islands were sold to the German Empire in 1899, after Spain withdrew from the Pacific in the aftermath of the Spanish–American War. Chuuk became a possession of the Empire of Japan under a mandate from the League of Nations following Germany's defeat in World War I. During World War II, Truk Lagoon was the Empire of Japan's main base in the South Pacific theatre. Truk was a fortified base for Japanese operations against Allied forces in New Guinea and the Solomon Islands, serving as the forward anchorage for the Imperial Japanese Navy. Truk Lagoon was considered the most formidable of all Japanese strongholds in the Pacific. On the various islands, the Japanese Civil Engineering Department and Naval Construction Department had built roads, trenches and caves. Five airstrips, seaplane bases, a torpedo boat station, submarine repair shops, a communications center and a radar station were constructed during the war.
Protecting these various facilities were coastal defense guns and mortar emplacements. The Japanese garrison consisted of 27,856 IJN men, under the command of Vice Admiral Masami Kobayashi Vice Admiral Chuichi Hara, 16,737 IJA men, under the command of Major General Kanenobu Ishuin. Due to its heavy fortifications, both natural and manmade, the base at Truk was known to Allied forces as "the Gibraltar of the Pacific."A significant portion of the Japanese fleet was based at Truk, with its administrative center on Tonoas. At anchor in the lagoon could be found the IJN's battleships, aircraft carriers, destroyers, cargo ships, gunboats, landing craft, submarines. In particular and Musashi, the largest battleships built, were stationed at Truk for months around 1943, unable to participate in battle due to lack of air cover; some have described Truk as Japan's equivalent of the Americans' Pearl Harbor, in that it was their respective nation's largest forward naval base. In 1944, Truk's capacity as a naval base was destroyed through naval air attack.
Forewarned by intelligence a week before the US raid, the Japanese had withdrawn their larger warships to Palau. Once the American forces captured the Marshall Islands, they used them as a base from which to launch an early morning attack on February 17, 1944 against Truk Lagoon. Operation Hailstone lasted for three days, as American carrier-based planes sank twelve smaller Japanese warships and thirty-two merchant ships, while destroying 275 aircraft on the ground; the consequences of the attack made "Truk lagoon the biggest graveyard of ships in the world."The attacks for the most part ended Truk as a major threat to Allied operations in the central Pacific. The Japanese garrison on Eniwetok was denied any realistic hope of reinforcement and support during the invasion that began on February 18, 1944 assisting U. S. forces in their conquest of that island. Truk was isolated by Allied forces, as they continued their advance towards Japan, by invading other Pacific islands, such as Guam, Saipan and Iwo Ji
Espiritu Santo is the largest island in the nation of Vanuatu, with an area of 3,955.5 km2 and a population of around 40,000 according to the 2009 census. The island belongs to the archipelago of the New Hebrides in the Pacific region of Melanesia, it is in the Sanma Province of Vanuatu. The town of Luganville, on Espiritu Santo's southeast coast, is Vanuatu's second-largest settlement and the provincial capital. Roads run north and west from Luganville, but most of the island is far from the limited road network. Around Espiritu Santo lie a number of small islets. Vanuatu's highest peak is the 1879 metre Mount Tabwemasana in west-central Espiritu Santo. In 1998, Espiritu Santo hosted the Melanesia Cup. A Spanish expedition led by Portuguese explorer Pedro Fernandes de Queirós, established a settlement in 1606 at Big Bay on the north side of the island. Espiritu Santo takes its name from Queirós, who named the entire island group La Austrialia del Espíritu Santo in acknowledgment of the Spanish king's descent from the royal House of Austria, believing he had arrived in the Great Southern Continent, Terra Australis.
During the time of the British–French Condominium, Hog Harbour, on the northeast coast, was the site of the British district administration, while Segond, near Luganville was the French district administration. During World War II after the Japanese attack on Pearl Harbor, the island was used by American naval and air forces as a military supply and support base, naval harbor, airfield. In fictionalized form, this was the locale of James Michener's Tales of the South Pacific, of the following Rodgers and Hammerstein musical, South Pacific; the presence of the Americans contributed to the island's tourism in scuba diving, as the Americans dumped most of their used military and naval equipment, their refuse, at what is now known as "Million Dollar Point". A shipwreck off Espiritu Santo, that of the SS President Coolidge, is a popular diving spot; the SS President Coolidge was a converted luxury liner that hit a sea mine during the war and was sunk. Between May and August 1980 the island was the site of a rebellion during the transfer of power over the colonial New Hebrides from the condominium to the independent Vanuatu.
Jimmy Stevens' Nagriamel movement, in alliance with private French interests and backed by the Phoenix Foundation and American libertarians hoping to establish a tax-free haven, declared the island of Espiritu Santo to be independent of the new government. The "Republic of Vemerana" was proclaimed on May 28. France recognized the independence on June 3. On June 5, the tribal chiefs of Santo named the French Ambassador Philippe Allonneau the "King of Vemerana", Jimmy Stevens became the Prime Minister. Luganville is renamed Allonneaupolis. Next, negotiations with Port-Vila failed, from July 27 to August 18, British Royal Marines and a unit of the French Garde Mobile were deployed to the Vanuatu's capital island, but they did not invade Espiritu Santo as the soon-to-be government had hoped; the troops were recalled shortly before independence. Following independence, now governed by Father Walter Lini, requested assistance from Papua New Guinea, whose army invaded and conquered Espiritu Santo, keeping it in Vanuatu.
Espiritu Santo, with many wrecks and reefs to be explored, is a popular tourist destination for divers. Champagne Beach draws tourists with clear waters; the "Western Side" of the island contains many caves which can be explored, cruise ships stop in at Luganville. The local people make their living by supporting the tourist trade, by cash-crop farming copra, but some cocoa beans and kava, as well as peanuts, or by subsistence farming and fishing. Most of the people are Christians; the largest church groups on the island are the Presbyterian Church of Vanuatu, the Roman Catholic Church, the Church of Melanesia. Active are the Apostolic Church, the Church of Christ, the Seventh-day Adventist Church, others. However, in many villages in Big Bay and South Santo, the people are "heathen", a term that in Vanuatu has no pejorative connotation — it denotes someone who has not embraced Christianity. Customary beliefs of a more modern sort are found among followers of the Nagriamel movement based in Fanafo.
For all of Espiritu Santo's people, custom plays a large part in their lives, regardless of their religion. The chief system continues in most areas; the people of Santo face some health problems malaria and tuberculosis. Although there is a hospital, most local people consult either their own witch doctor or medical clinics set up by western missionaries. Kava is the popular drug of the island. With the rising number of adults using alcohol, there is a rising crime rate involving violence toward women, tribal warfare. Luganville is the only true town on the island. From Luganville, three "main roads" emerge. Main Street leaves the town to the west and winds along the south coast of the island for about 40 km ending at the village of Tasiriki on the southwest coast. Canal Road runs along the southern and eastern coasts of the island, north through Hog Harbor and Golden Beach, ending at Port Olry. Big Bay Highway splits off from Canal Road near Turtle Bay on the east coast, runs west to the mountains, it leads north to Big Bay.
The international airport is about five km east of the center of Luganville. Numerous rivers run to the
China the People's Republic of China, is a country in East Asia and the world's most populous country, with a population of around 1.404 billion. Covering 9,600,000 square kilometers, it is the third- or fourth-largest country by total area. Governed by the Communist Party of China, the state exercises jurisdiction over 22 provinces, five autonomous regions, four direct-controlled municipalities, the special administrative regions of Hong Kong and Macau. China emerged as one of the world's earliest civilizations, in the fertile basin of the Yellow River in the North China Plain. For millennia, China's political system was based on hereditary monarchies, or dynasties, beginning with the semi-legendary Xia dynasty in 21st century BCE. Since China has expanded, re-unified numerous times. In the 3rd century BCE, the Qin established the first Chinese empire; the succeeding Han dynasty, which ruled from 206 BC until 220 AD, saw some of the most advanced technology at that time, including papermaking and the compass, along with agricultural and medical improvements.
The invention of gunpowder and movable type in the Tang dynasty and Northern Song completed the Four Great Inventions. Tang culture spread in Asia, as the new Silk Route brought traders to as far as Mesopotamia and Horn of Africa. Dynastic rule ended in 1912 with the Xinhai Revolution; the Chinese Civil War resulted in a division of territory in 1949, when the Communist Party of China established the People's Republic of China, a unitary one-party sovereign state on Mainland China, while the Kuomintang-led government retreated to the island of Taiwan. The political status of Taiwan remains disputed. Since the introduction of economic reforms in 1978, China's economy has been one of the world's fastest-growing with annual growth rates above 6 percent. According to the World Bank, China's GDP grew from $150 billion in 1978 to $12.24 trillion by 2017. Since 2010, China has been the world's second-largest economy by nominal GDP and since 2014, the largest economy in the world by purchasing power parity.
China is the world's largest exporter and second-largest importer of goods. China is a recognized nuclear weapons state and has the world's largest standing army and second-largest defense budget; the PRC is a permanent member of the United Nations Security Council as it replaced the ROC in 1971, as well as an active global partner of ASEAN Plus mechanism. China is a leading member of numerous formal and informal multilateral organizations, including the Shanghai Cooperation Organization, WTO, APEC, BRICS, the BCIM, the G20. In recent times, scholars have argued that it will soon be a world superpower, rivaling the United States; the word "China" has been used in English since the 16th century. It is not a word used by the Chinese themselves, it has been traced through Portuguese and Persian back to the Sanskrit word Cīna, used in ancient India."China" appears in Richard Eden's 1555 translation of the 1516 journal of the Portuguese explorer Duarte Barbosa. Barbosa's usage was derived from Persian Chīn, in turn derived from Sanskrit Cīna.
Cīna was first used including the Mahābhārata and the Laws of Manu. In 1655, Martino Martini suggested that the word China is derived from the name of the Qin dynasty. Although this derivation is still given in various sources, it is complicated by the fact that the Sanskrit word appears in pre-Qin literature; the word may have referred to a state such as Yelang. The meaning transferred to China as a whole; the origin of the Sanskrit word is still a matter of debate, according to the Oxford English Dictionary. The official name of the modern state is the "People's Republic of China"; the shorter form is "China" Zhōngguó, from zhōng and guó, a term which developed under the Western Zhou dynasty in reference to its royal demesne. It was applied to the area around Luoyi during the Eastern Zhou and to China's Central Plain before being used as an occasional synonym for the state under the Qing, it was used as a cultural concept to distinguish the Huaxia people from perceived "barbarians". The name Zhongguo is translated as "Middle Kingdom" in English.
Archaeological evidence suggests that early hominids inhabited China between 2.24 million and 250,000 years ago. The hominid fossils of Peking Man, a Homo erectus who used fire, were discovered in a cave at Zhoukoudian near Beijing; the fossilized teeth of Homo sapiens have been discovered in Fuyan Cave in Hunan. Chinese proto-writing existed in Jiahu around 7000 BCE, Damaidi around 6000 BCE, Dadiwan from 5800–5400 BCE, Banpo dating from the 5th millennium BCE; some scholars have suggested. According to Chinese tradition, the first dynasty was the Xia, which emerged around 2100 BCE; the dynasty was considered mythical by historians until scientific excavations found early Bronze Age sites at Erlitou, Henan in 1959. It remains unclear whether these sites are the remains of the Xia dynasty or of another culture from the same period; the succeeding Shang dynasty is the earliest to be confirmed by contemporary records. The Shang ruled the plain of the Yellow River in eastern China from the 17th to the 11th century BCE.
Their oracle bone script
The Hedgehog was a forward-throwing anti-submarine weapon, used during the Battle of the Atlantic in the Second World War. The device, developed by the Royal Navy, fired up to 24 spigot mortars ahead of a ship when attacking a U-boat, it was deployed on convoy escort warships such as destroyers and corvettes to supplement the depth charges. As the mortar projectiles employed contact fuzes rather than time or barometric fuzes, detonation occurred directly against a hard surface such as the hull of a submarine making it more deadly than depth charges, which relied on damage caused by hydrostatic shockwaves. Statistics show that during WWII out of 5,174 British depth charge attacks there were 85.5 kills: a ratio of 60.5 to 1. In comparison, the Hedgehog made 268 attacks for 47 kills: a ratio of 5.7 to 1. The "Hedgehog", so named because the empty rows of its launcher spigots resembled the spines of a hedgehog, was a replacement for the unsuccessful Fairlie Mortar, trialled aboard HMS Whitehall in 1941.
Although a failure, the Fairlie was designed to fire depth charges ahead of a ship when attacking a submarine. This principle of forward-firing projectiles was considered viable; this secret research by the Directorate of Miscellaneous Weapons Development led to the development of the Hedgehog. The weapon was a multiple'spigot mortar' or spigot discharger, a type of weapon developed between the wars by Lieutenant Colonel Stewart Blacker, RA; the spigot mortar was based on early infantry trench mortars. The spigot design allowed a single device to fire warheads of varying size; the propelling charge was part of the main weapon and worked against a rod set in the baseplate which fitted inside a tubular tail of the'bomb'. This principle was first used on the Blacker Bombard 29 mm Spigot Mortar and the PIAT anti-tank weapon; the adaptation of the bombard for naval use was made in partnership with MIR under Major Millis Jefferis who had taken Blacker's design and brought it into use with Army. The weapon fires a salvo of 24 bombs in an arc, aimed to land in a circular or elliptical area about 100 feet in diameter at a fixed point about 250 yards directly ahead of the attacking ship.
The mounting was fixed but was replaced by a gyro-stabilised one to allow for the rolling and pitching of the attacking ship. The system was developed to solve the problem of the target submarine disappearing from the attacking ship's ASDIC when the ship came within the sonar's minimum range. Due to the speed of sound in water, the time taken for the'ping' echo to return to the attacking ship from the target submarine became too short to allow the human operator to distinguish the returning audible echo from that of the initial sound pulse emitted by the sonar – the so-called "instantaneous echo", where the output sound pulse and returning echo merge; this "blind spot" allowed the submarine to make evasive manoeuvres undetected while the ship was out of range for depth charge attack. Hence, the submarine was invisible to the sonar as the ship came within the sonar's minimum range; the solution was a weapon mounted on the foredeck that discharged the projectiles up and over that carrying ship's bow, to land in the water some distance in front of the ship while the submarine was still outside the sonar's minimum range.
The Hedgehog entered service in 1942. Carrying a Torpex charge weighing 16 kg, each mortar had a diameter of 18 cm and weighed about 29.5 kg. The projectiles were angled so they would land in a circular shape with a diameter of 40 m about 180 m ahead of a stationary ship; the projectiles would sink at about 7 m/s. They would reach a submerged U-boat, for example at 200 ft in under 9 seconds. Sympathetic detonation of projectiles near those contacting hard surfaces was a possibility, but the number of explosions counted was fewer than the number of projectiles launched; the prototype launcher was tested aboard HMS Westcott in 1941, but there were no submarine kills until November 1942, after it had been installed aboard one hundred ships. Initial success rates – of about 5% – were only better than depth charges. Swells and spray covered the launcher during heavy North Atlantic weather, subsequent attempts to launch revealed firing circuit problems launching an incomplete pattern; the disappointment of a quiet miss discouraged crews who might otherwise assume depth charge explosions had damaged their target or at least frightened the enemy.
The Royal Navy launched Hedgehog so in early 1943 that a directive was issued ordering captains of ships equipped with Hedgehog to report why they had not used Hedgehog on an underwater contact. The results were blamed on low confidence in the weapon. However, after an officer from the DMWD was sent to Londonderry Port, where the convoy crews were based, with better training and shipwide talks on examples of successful Hedgehog attacks, the kill rate improved considerably. By the end of the war, statistics showed that on average, one in every five attacks made by Hedgehog resulted in a kill. In response to this new deadly threat to its U-boats, the Kriegsmarine brought forward its programme of acoustic torpedoes in 1943, beginning with the Falke; these new "homing" torpedoes could be employed without the use of a periscope, providing submarines a better chance to remain undetected and evade counterattack. In the Pacific Theater, USS England sank six Japanese submarines in a matter of days with Hedgehog in May 1944.
In 1946, USS Solar was destroyed after a crewman accidentally dropped a Hedgehog charge near one of her main turret am
Oerlikon 20 mm cannon
The Oerlikon 20 mm cannon is a series of autocannons, based on an original German 20 mm Becker design that appeared early in World War I. It was produced by Oerlikon Contraves and others, with various models employed by both Allied and Axis forces during World War II, many versions still in use today. During World War I, the German industrialist Reinhold Becker developed a 20 mm caliber cannon, known now as the 20 mm Becker using the Advanced Primer Ignition blowback method of operation; this had a cyclic rate of fire of 300 rpm. It was used on a limited scale as an aircraft gun on Luftstreitkräfte warplanes, an anti-aircraft gun towards the end of that war; because the Treaty of Versailles banned further production of such weapons in Germany, the patents and design works were transferred in 1919 to the Swiss firm SEMAG based near Zürich. SEMAG continued development of the weapon, in 1924 had produced the SEMAG L, a heavier weapon that fired more powerful 20x100RB ammunition at a higher rate of fire, 350 rpm.
In 1924 SEMAG failed. The Oerlikon firm, named after the Zürich suburb of Oerlikon where it was based acquired all rights to the weapon, plus the manufacturing equipment and the employees of SEMAG. In 1927 the Oerlikon S was added to the existing product line; this fired a still larger cartridge to achieve a muzzle velocity of 830 m/s, at the cost of increased weight and a reduced rate of fire. The purpose of this development was to improve the performance of the gun as an anti-tank and anti-aircraft weapon, which required a higher muzzle velocity. An improved version known as the 1S followed in 1930. Three sizes of gun with their different ammunition and barrel length, but similar mechanisms, continued to be developed in parallel. In 1930 Oerlikon reconsidered the application of its gun in aircraft and introduced the AF and AL, designed to be used in flexible mounts, i.e. manually aimed by a gunner. The 15-round box magazine used by earlier versions of the gun was replaced by drum magazine holding 15 or 30 rounds.
In 1935 it made an important step by introducing a series of guns designed to be mounted in or on the wings of fighter aircraft. Designated with FF for Flügelfest meaning "wing-mounted", these weapons were again available in the three sizes, with designations FF, FFL and FFS; the FF fired a larger cartridge than the AF, 20x72RB, but the major improvement in these weapons was a significant increase in rate of fire. The FF weighed 24 kg and achieved a muzzle velocity of 550 to 600 m/s with a rate of fire of 520 rpm; the FFL of 30 kg fired a projectile at a muzzle velocity of 675 m/s with a rate of fire of 500 rpm. And the FFS, which weighed 39 kg, delivered a high muzzle velocity of 830 m/s at a rate of fire of 470 rpm. Apart from changes to the design of the guns for wing-mounting and remote control, larger drums were introduced as it would not be possible to exchange magazines in flight. For the FF series drum sizes of 45, 60, 75 and 100 rounds were available, but most users chose the 60-round drum.
The 1930s were a period of global re-armament, a number of foreign firms took licenses for the Oerlikon family of aircraft cannon. In France, Hispano-Suiza manufactured development of the FFS as the Hispano-Suiza HS.7 and Hispano-Suiza HS.9, for installation between the cylinder banks of its V-12 engines. In Germany, Ikaria further developed the FF gun as firing 20x80RB ammunition, and the Imperial Japanese Navy, after evaluating all three guns, ordered developments of the FF and FFL as the Type 99-1 and Type 99-2. The incorporation of the improvements of the FFS in a new anti-aircraft gun produced, in 1938, the Oerlikon SS. Oerlikon realized further improvements in rate of fire on the 1SS of 1942, the 2SS of 1945 which achieved 650 rpm. However, it was the original SS gun, adopted as anti-aircraft gun, being widely used by Allied navies during World War II; this gun used a 400-grain charge of IMR 4831 smokeless powder to propel a 2,000-grain projectile at 2,800 feet per second. The Oerlikon FF was installed as armament on some fighters of the 1930s, such as the Polish PZL P.24G.
Locally produced derivatives of the Oerlikon cannon were used much more extensively, on aircraft, on ships and on land. In the air, the Ikaria MG FF was used as armament on a number of German aircraft, of which the most famous is the Messerschmitt Bf 109; the Japanese Navy used their copy of the FF, designated the Type 99 Mark One cannon on a number of types including the Mitsubishi A6M Zero. In the war, they equipped fighters including the Zero with the Type 99 Mark Two, a version of the more powerful and faster-firing Oerlikon FFL; the French firm of Hispano-Suiza was a manufacturer of aircraft engines, it marketed the moteur-canon combination of its 12X and 12Y engines with a H. S.7 or H. S.9 cannon installed between the cylinder banks. The gun fired through the hollow propeller hub, this being elevated above the crankcase by the design of the gearing; such armament was installed on the Morane-Saulnier M. S.406 and some other types. Similar German installations of the MG FF were not successful.
The Oerlikon became best known in its naval applications. The Oerlikon was not looked upon favorably by the Royal Navy as a short-range anti-aircraft gun. All through 1937-1938 Lord Louis Mountbatten a Captain in the Royal Navy, waged a lone campaign within the Royal Navy to set up an unprejudiced trial for the Oerlikon 20 mm gun, but it was all in vain, it was not until the Commander-in-Chief of the Home Fleet, Admiral Sir Roger Backhouse, was appointed First Sea Lord tha
Anti-submarine warfare is a branch of underwater warfare that uses surface warships, aircraft, or other submarines to find and deter, damage, or destroy enemy submarines. Successful anti-submarine warfare depends on a mix of sensor and weapon technology and experience. Sophisticated sonar equipment for first detecting classifying and tracking the target submarine is a key element of ASW. To destroy submarines, both torpedos and naval mines are used, launched from air and underwater platforms. ASW involves protecting friendly ships; the first attacks on a ship by an underwater vehicle are believed to have been during the American Revolutionary War, using what would now be called a naval mine but what was called a torpedo, though various attempts to build submarines had been made before this. The first self-propelled torpedo was launched from surface craft; the first submarine with a torpedo was Nordenfelt I built in 1884-1885, though it had been proposed earlier. By the outbreak of the Russo-Japanese War all the large navies except the German had acquired submarines.
In 1904 all still defined the submarine as an experimental vessel and did not put it into operational use. There were no means to detect submerged U-boats, attacks on them were limited at first to efforts to damage their periscopes with hammers; the Royal Navy torpedo establishment, HMS Vernon, studied explosive grapnel sweeps. A similar approach featured a string of 70 lb charges on a floating cable, fired electrically. Tried were dropping 18.5 lb hand-thrown guncotton bombs. The Lance Bomb was developed, also. Firing Lyddite shells, or using trench mortars, was tried. Use of nets to ensnare U-boats was examined, as was a destroyer, HMS Starfish, fitted with a spar torpedo. To attack at set depths, aircraft bombs were attached to lanyards. Problems with the lanyards tangling and failing to function led to the development of a chemical pellet trigger as the Type B; these were effective at a distance of around 20 ft. The best concept arose in a 1913 RN Torpedo School report, describing a device intended for countermining, a "dropping mine".
At Admiral John Jellicoe's request, the standard Mark II mine was fitted with a hydrostatic pistol preset for 45 ft firing, to be launched from a stern platform. Weighing 1,150 lb, effective at 100 ft, the "cruiser mine" was a potential hazard to the dropping ship. During the First World War, submarines were a major threat, they operated in North Sea, Black Sea and Mediterranean as well as the North Atlantic. They had been limited to calm and protected waters; the vessels used to combat them were a range of fast surface ships using guns and good luck. They relied on the fact a submarine of the day was on the surface for a range of reasons, such as charging batteries or crossing long distances; the first approach to protect warships was chainlink nets strung from the sides of battleships, as defense against torpedoes. Nets were deployed across the mouth of a harbour or naval base to stop submarines entering or to stop torpedoes of the Whitehead type fired against ships. British warships were fitted with a ram with which to sink submarines, U-15 was thus sunk in August 1914.
RN in June 1915 began operational trials of the Type D depth charge, with a 300 lb charge of TNT and a hydrostatic pistol, firing at either 40 or 80 ft, believed to be effective at a distance of 140 ft. In July 1915, the British Admiralty set up the Board of Invention and Research to evaluate suggestions from the public as well as carrying out their own investigations; some 14,000 suggestions were received about combating submarines. In December 1916, the RN set up its own Anti-Submarine Division but relations with the BIR were poor. After 1917 most ASW work was carried out by ASD. In the U. S. a Naval Consulting Board was set up in 1915 to evaluate ideas. After American entry into the war in 1917, they encouraged work on submarine detection; the U. S. National Research Council, a civilian organization, brought in British and French experts on underwater sound to a meeting with their American counterparts in June 1917. In October 1918, there was a meeting in Paris on "supersonics", a term used for echo-ranging, but the technique was still in research by the end of the war.
The first recorded sinking of a submarine by depth charge was U-68, sunk by Q-ship HMS Farnborough off Kerry, Ireland 22 March 1916. By early 1917, the Royal Navy had developed indicator loops which consisted of long lengths of cables lain on the seabed to detect the magnetic field of submarines as they passed overhead. At this stage they were used in conjunction with controlled mines which could be detonated from a shore station once a'swing' had been detected on the indicator loop galvanometer. Indicator loops used with controlled mining were known as'guard loops'. By July 1917, depth charges had developed to the extent that settings of between 50–200 ft were possible; this design would remain unchanged through