I've noticed over the years that a lot of people confuse elements of the ULTRA/ENIGMA story, both in the press, general conversation and indeed on this board. So, I've come up with a few Q/As. Q. What was ULTRA intelligence? A. Ultra actually had different meanings depending on the point of time being discussed. Initially it was a form of secret classification. At the time the highest British security classification for material was 'Most Secret'. The sensitivity of the material gathered from Axis message traffic was deemed to be highly extreme, and to differentiate this material from other 'Most Secret' documents the prefix 'Ultra' was added. Thus material gathered from this source was known as 'Most Secret Ultra'. When the US entered the war the classification was altered to 'Top Secret Ultra' to match US security classification standards. As a result all high-level radio/teleprinter traffic intercepted was placed under the category of Ultra. So when people are talking about 'Ultra' that is what they are talking about. Q. What was Enigma? A. Enigma was the name of the machine cipher system designed by Arthur Scherbius and first patented in 1918. Initially the system was designed for commercial use to protect corporate wireless traffic. In 1925 the German Navy adopted the enigma system and added a number of features to make the system considerably more secure. By 1928 the German Army had also adopted a version of the system, and by the outbreak of war various versions of the system were in use, not just among the German military, but also the Abwehr, railway system, etc, it was also being widely used by other Axis powers. Its advantage was its relative portability combined with what was considered first-rate security. Q. Did the Axis powers use any other systems? A. Yes. A number of different systems were used, perhaps most notably the Siemens and Halske T52 and the Lorenz SZ/40 and SZ/42 machines. These were teleprinter cipher systems. They were also far more secure than Enigma. Their drawback was a lack of portability. As a result they tended to be used further up the chain of command, namely the German High Command to Generals. Q. What is Bletchley Park? A. Bletchley Park is a small estate in Buckinghamshire, some 40 miles North of London. Shortly prior to the outbreak of the war it was purchased on the behalf of the Government Code and Cypher School (GC&CS) and the Secret Intelligence Service (SIS, often known as MI6) by Admiral Hugh Sinclair the then head of SIS. Bletchley Park was to serve to house both GC&CS and SIS when they were evacuated from London on the outbreak of the war. However, Bletchley Park served only as the primary war station and head quarters of GC&CS, numerous out stations and offices were maintained in relatively nearby locations. Q. What was GC&CS? A. As noted GC&CS stood for the Government Code and Cypher School, which was formed in 1919 as an amalgamation of the Army and Royal Navy's cryptanalysis departments. GC&CS had two main roles. Firstly, and ostensibly, it existed to provide advice and training to British state institutions/services in maintaining secure communications. Secondly, and more famously, it served as a centralised cryptanalysis institution for the British state. Following the war it was re-dubbed the Government Communications Headquarters (GCHQ) and moved to Cheltenham. Q. What was a Bombe machine? A. Named after the Polish machine bomba, which had been used with some success in breaking into Enigma traffic, it was a machine designed by Alan Turing and improved by Gordon Welchman to aid British cryptanalysts in reading Enigma traffic. The machine did not actually break the cipher, rather it was a labour saving device which removed possibilities. Q. What was a Colossus Computer? A. The Colossus Computers were electro-mechanical machines (some debate exists as to whether they were true computers as we understand the term today) designed to aid cryptanalysts read messages enciphered by Lorenz SZ/40 and SZ/42 machines. It was designed by a team headed by Tommy Flowers (a post office engineer), and contrary to popular belief was not designed by Alan Turing. Q. What were Purple and Magic? A. In 1939 Germany provided Japan with a modified Enigma system. The traffic emerging from this system was dubbed by American cryptanalysts as 'Purple'. The name derives from the two code names given to the previous Japanese systems, which were Red and Blue. Both systems proved readable, the new system on the other hand was not. The new system was dubbed purple (a mixture of the two other colours used previously). Magic was the code name for the combined US cryptanalysis project during the Second World War. Q. The US and Britain were reading Purple traffic before the attack on Pearl Harbour, does that mean that they had prior knowledge of the attack? A. No. Purple was confined to Japanese diplomatic traffic. The Japanese military services employed different systems. At the highest level the Navy employed a system known as JN-25. JN-25 was regularly changed and improved making the process of reading traffic much harder. For example, by late 1940 in-roads were beginning to be made and a tiny fraction of traffic was beginning to be read. Then on August 1, 1941 the Japanese introduced a new 50,000-group list of additives which set the cryptanalysts back to the drawing board to start over.