Second Battle of El AlameinThe Second Battle of El Alamein (23 October – 11 November 1942) was a battle of the Second World War that took place near the Egyptian railway halt of El Alamein. The First Battle of El Alamein and the Battle of Alam el Halfa had prevented the Axis from advancing further into Egypt. In August 1942, General Claude Auchinleck had been relieved as Commander-in-Chief of Middle East Command and his successor, Lieutenant-General William Gott was killed on his way to replace him as commander of the Eighth Army.
Known-plaintext attackThe known-plaintext attack (KPA) is an attack model for cryptanalysis where the attacker has access to both the plaintext (called a crib) and its encrypted version (ciphertext). These can be used to reveal further secret information such as secret keys and code books. The term "crib" originated at Bletchley Park, the British World War II decryption operation, where it was defined as:A plain language (or code) passage of any length, usually obtained by solving one or more cipher or code messages, and occurring or believed likely to occur in a different cipher or code message, which it may provide a means of solving.
Battle of BritainThe Battle of Britain (die Luftschlacht um England, "the air battle for England") was a military campaign of the Second World War, in which the Royal Air Force (RAF) and the Fleet Air Arm (FAA) of the Royal Navy defended the United Kingdom (UK) against large-scale attacks by Nazi Germany's air force, the Luftwaffe. It was the first major military campaign fought entirely by air forces. The British officially recognise the battle's duration as being from 10 July until 31 October 1940, which overlaps the period of large-scale night attacks known as the Blitz, that lasted from 7 September 1940 to 11 May 1941.
Direction findingDirection finding (DF), or radio direction finding (RDF), is - in accordance with International Telecommunication Union (ITU) - defined as radio location that uses the reception of radio waves to determine the direction in which a radio station or an object is located. This can refer to radio or other forms of wireless communication, including radar signals detection and monitoring (ELINT/ESM). By combining the direction information from two or more suitably spaced receivers (or a single mobile receiver), the source of a transmission may be located via triangulation.
Colossus computerColossus was a set of computers developed by British codebreakers in the years 1943–1945 to help in the cryptanalysis of the Lorenz cipher. Colossus used thermionic valves (vacuum tubes) to perform Boolean and counting operations. Colossus is thus regarded as the world's first programmable, electronic, digital computer, although it was programmed by switches and plugs and not by a stored program. Colossus was designed by General Post Office (GPO) research telephone engineer Tommy Flowers to solve a problem posed by mathematician Max Newman at the Government Code and Cypher School (GC&CS) at Bletchley Park.
Surrender of JapanThe surrender of the Empire of Japan in World War II was announced by Emperor Hirohito on 15 August and formally signed on 2 September 1945, bringing the war's hostilities to a close. By the end of July 1945, the Imperial Japanese Navy (IJN) had become incapable of conducting major operations and an Allied invasion of Japan was imminent. Together with the United Kingdom and China, the United States called for the unconditional surrender of the Japanese armed forces in the Potsdam Declaration on 26 July 1945—the alternative being "prompt and utter destruction".
Fish (cryptography)Fish (sometimes FISH) was the UK's GC&CS Bletchley Park codename for any of several German teleprinter stream ciphers used during World War II. Enciphered teleprinter traffic was used between German High Command and Army Group commanders in the field, so its intelligence value (Ultra) was of the highest strategic value to the Allies. This traffic normally passed over landlines, but as German forces extended their geographic reach beyond western Europe, they had to resort to wireless transmission.
High-frequency direction findingHigh-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.
Hut 8Hut 8 was a section in the Government Code and Cypher School (GC&CS) at Bletchley Park (the British World War II codebreaking station, located in Buckinghamshire) tasked with solving German naval (Kriegsmarine) Enigma messages. The section was led initially by Alan Turing. He was succeeded in November 1942 by his deputy, Hugh Alexander. Patrick Mahon succeeded Alexander in September 1944. Hut 8 was partnered with Hut 4, which handled the translation and intelligence analysis of the raw decrypts provided by Hut 8.
Battle of Cape MatapanThe Battle of Cape Matapan (Ναυμαχία του Ταινάρου) was a naval battle during the Second World War between the Allies, represented by the navies of the United Kingdom and Australia, and the Royal Italian navy, from 27 to 29 March 1941. Cape Matapan is on the south-western coast of the Peloponnesian Peninsula of Greece.
