|
Atlantic Gap
The Mid-Atlantic gap is a geographical term applied to an undefended area of the Atlantic Ocean during the Battle of the Atlantic in the Second World War. The region was beyond the reach of land-based RAF Coastal Command antisubmarine (A/S) aircraft. This resulted in heavy merchant shipping losses to U-boats. It is frequently known as The Black Pit, as well as the Atlantic Gap, Air Gap, Greenland Gap, Black Gap, or just "the Gap". The gap was eventually closed in May 1943, as growing numbers of VLR Liberators (Very Long Range models) and escort carriers became available, and as basing problems were addressed. History The Royal Air Force (RAF)'s Coastal Command, when it was created in 1936, was given responsibility for antisubmarine warfare (A/S or ASW) patrol. It was equipped only with small numbers of short-ranged aircraft, the most common being the Avro Anson (which was obsolete by the start of the Second World War) and Vickers Vildebeest (which was obsolete); for a time, short ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Battle Of The Atlantic 1941 Map
''The'' is a grammatical article in English, denoting nouns that are already or about to be mentioned, under discussion, implied or otherwise presumed familiar to listeners, readers, or speakers. It is the definite article in English. ''The'' is the most frequently used word in the English language; studies and analyses of texts have found it to account for seven percent of all printed English-language words. It is derived from gendered articles in Old English which combined in Middle English and now has a single form used with nouns of any gender. The word can be used with both singular and plural nouns, and with a noun that starts with any letter. This is different from many other languages, which have different forms of the definite article for different genders or numbers. Pronunciation In most dialects, "the" is pronounced as (with the voiced dental fricative followed by a schwa) when followed by a consonant sound, and as (homophone of the archaic pronoun ''thee' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Depth Charge
A depth charge is an anti-submarine warfare (ASW) weapon designed to destroy submarine A submarine (often shortened to sub) is a watercraft capable of independent operation underwater. (It differs from a submersible, which has more limited underwater capability.) The term "submarine" is also sometimes used historically or infor ...s by detonating in the water near the target and subjecting it to a destructive shock factor, hydraulic shock. Most depth charges use high explosives with a fuze set to detonate the charge, typically at a specific depth from the surface. Depth charges can be dropped by ships (typically fast, agile surface combatants such as destroyers or frigates), patrol aircraft and helicopters. Depth charges were developed during World War I, and were one of the first viable methods of attacking a submarine underwater. They were widely used in World War I and World War II, and remained part of the anti-submarine arsenals of many navies during the Cold War, duri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High Frequency Direction Finding
High-frequency direction finding, usually known by its abbreviation HF/DF or nickname huff-duff, is a type of radio direction finder (RDF) introduced in World War II. High frequency (HF) refers to a radio band that can effectively communicate over long distances; for example, between U-boats and their land-based headquarters. HF/DF was primarily used to catch enemy radios while they transmitted, although it was also used to locate friendly aircraft as a navigation aid. The basic technique remains in use as one of the fundamental disciplines of signals intelligence, although typically incorporated into a larger suite of radio systems and radars instead of being a stand-alone system. In earlier RDF systems, the operator mechanically rotated a loop antenna or solenoid and listened for peaks or nulls in the signal to determine the bearing to the transmitter. This took considerable time, on the order of a minute or more. Radio operators could avoid being located by keeping their messag ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convoy ON 136
A convoy is a group of vehicles, typically motor vehicles or ships, traveling together for mutual support and protection. Often, a convoy is organized with armed defensive support and can help maintain cohesion within a unit. It may also be used in a non-military sense, for example when driving through remote areas. Naval convoys Age of Sail Naval convoys have been in use for centuries, with examples of merchant ships traveling under naval protection dating to the 12th century. The use of organized naval convoys dates from when ships began to be separated into specialist classes and national navies were established. By the French Revolutionary Wars of the late 18th century, effective naval convoy tactics had been developed to ward off pirates and privateers. Some convoys contained several hundred merchant ships. The most enduring system of convoys were the Spanish treasure fleets, that sailed from the 1520s until 1790. When merchant ships sailed independently, a privateer coul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Convoy ON 127
Convoy ON 127 was a trade convoy of merchant ships during the second World War. It was the 127th of the numbered series of ON convoys Outbound from the British Isles to North America and the only North Atlantic trade convoy of 1942 or 1943 where all U-boats deployed against the convoy launched torpedoes.Rohwer&Hummelchen 1992 p. 161 The ships departed Liverpool on 4 September 1942Hague 2000 p. 158 and were met at noon on 5 September by the Royal Canadian Navy Mid-Ocean Escort Force Group C-4 consisting of the and the with the s , , , and . ''St. Croix''s commanding officer, acting Lieutenant Commander A. H. "Dobby" Dobson RCNR, was the senior officer of the escort group. The Canadian ships carried type 286 meter-wavelength radar but none of their sets were operational.Blair 1998 p. 30 ''Celandine'' carried Type 271 centimeter-wavelength radar. None of the ships carried HF/DF high-frequency direction finding sets. Background As western Atlantic coastal convoys brought an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultra (cryptography)
Ultra was the designation adopted by United Kingdom, British military intelligence in June 1941 for wartime signals intelligence obtained by breaking high-level encrypted enemy radio and teleprinter communications at the Government Code and Cypher School (GC&CS) at Bletchley Park. ''Ultra'' eventually became the standard designation among the western Allies of World War II, Allies for all such intelligence. The name arose because the intelligence obtained was considered more important than that designated by the highest British Classified information, security classification then used (''Most Secret'' and so was regarded as being ''Ultra Secret''. Several other cryptonyms had been used for such intelligence. The code name "Boniface" was used as a cover name for ''Ultra''. In order to ensure that the successful code-breaking did not become apparent to the Germans, British intelligence created a fictional MI6 master spy, Boniface, who controlled a fictional series of agents throug ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enigma Machine
The Enigma machine is a cipher device developed and used in the early- to mid-20th century to protect commercial, diplomatic, and military communication. It was employed extensively by Nazi Germany during World War II, in all branches of the Wehrmacht, German military. The Enigma machine was considered so secure that it was used to encipher the most top-secret messages. The Enigma has an electromechanical Rotor machine, rotor mechanism that scrambles the 26 letters of the alphabet. In typical use, one person enters text on the Enigma's keyboard and another person writes down which of the 26 lights above the keyboard illuminated at each key press. If plaintext is entered, the illuminated letters are the ciphertext. Entering ciphertext transforms it back into readable plaintext. The rotor mechanism changes the electrical connections between the keys and the lights with each keypress. The security of the system depends on machine settings that were generally changed daily, based ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kriegsmarine
The (, ) was the navy of Nazi Germany from 1935 to 1945. It superseded the Imperial German Navy of the German Empire (1871–1918) and the inter-war (1919–1935) of the Weimar Republic. The was one of three official military branch, branches, along with the and the , of the , the German armed forces from 1935 to 1945. In violation of the Treaty of Versailles, the grew rapidly during German rearmament, German naval rearmament in the 1930s. The 1919 treaty had limited the size of the German navy and prohibited the building of submarines. ships were deployed to the waters around Spain during the Spanish Civil War (1936–1939) under the guise of enforcing non-intervention in the Spanish Civil War, non-intervention, but in reality supporting the Francoist Spain, Nationalists against the Second Spanish Republic, Spanish Republicans. In January 1939, Plan Z, a massive shipbuilding programme, was ordered, calling for surface naval parity with the United Kingdom, British Royal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bletchley Park
Bletchley Park is an English country house and Bletchley Park estate, estate in Bletchley, Milton Keynes (Buckinghamshire), that became the principal centre of Allies of World War II, Allied World War II cryptography, code-breaking during the Second World War. During World War II, the estate housed the Government Code and Cypher School (GC&CS), which regularly penetrated the secret communications of the Axis Powers most importantly the German Enigma machine, Enigma and Lorenz cipher, Lorenz ciphers. The GC&CS team of codebreakers included John Tiltman, Dilwyn Knox, Alan Turing, Harry Golombek, Gordon Welchman, Conel Hugh O'Donel Alexander, Hugh Alexander, Donald Michie, W. T. Tutte, Bill Tutte and Stuart Milner-Barry. The team at Bletchley Park devised automatic machinery to help with decryption, culminating in the development of Colossus computer, Colossus, the world's first programmable digital electronic computer. Codebreaking operations at Bletchley Park ended in 1946 and al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pacific War
The Pacific War, sometimes called the Asia–Pacific War or the Pacific Theatre, was the Theater (warfare), theatre of World War II fought between the Empire of Japan and the Allies of World War II, Allies in East Asia, East and Southeast Asia, the Pacific Ocean, Pacific and Indian Oceans, and Oceania. It was geographically the largest theatre of the war, including the Pacific Ocean theater of World War II, Pacific Ocean theatre, the South West Pacific theater of World War II, South West Pacific theatre, the Second Sino-Japanese War, and the brief Soviet–Japanese War, and included some of the Largest naval battle in history, largest naval battles in history. War between Japan and the Republic of China (1912–1949), Republic of China had begun in 1937, with hostilities dating back to Japanese invasion of Manchuria, Japan's invasion of Manchuria in 1931, but the Pacific War is more widely accepted to have started in 1941, when the United States and United Kingdom entered the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Consolidated Liberator I
Consolidated Liberator I was the service name of the first Consolidated B-24 Liberator four-engined bombers to see use with the Royal Air Force (RAF). A small number of B-24s were purchased for the RAF but assessment showed that they were not suitable for use over Europe. They were however suitable for long range maritime reconnaissance and were put into use with RAF Coastal Command. Service history In August 1939, before the prototype had been completed, the United States Army Air Corps (USAAC) ordered 38 examples of the Consolidated B-24A (the first production variant). From this order, 20 aircraft (originally allocated serial numbers 40-2349 to 40-2368) were released for direct purchase by the RAF where it was given the service name Liberator B.Mk.I (from "Bomber Mark 1"). The twenty Liberator B.Mk.I were delivered to the RAF starting in mid 1941 and were given serial numbers ''AM910'' to ''AM929''. After a period of testing at the Aeroplane and Armament Experimental ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
