At the start of WWII, the US armed forces used various means for enciphering their confidential traffic. At the lowest level were hand ciphers. Above that were the M-94 and M-138 strip ciphers and at the top level a small number of highly advanced SIGABA cipher machines.

The Americans used the strip ciphers extensively however these were not only vulnerable to cryptanalysis but also difficult to use. Obviously a more modern and efficient means of enciphering was needed.

At that time Swedish inventor Boris Hagelin was trying to sell his cipher machines to foreign governments. He had already sold versions of his C-36, C-38 and B-211 cipher machines to European countries. He had also visited the United States in 1937 and 1939 in order to promote his C-36 machine and the electric C-38 with a keyboard called BC-38 but he was not successful (1). The Hagelin C-36 had 5 pin-wheels and the lugs on the drum were fixed in place. Hagelin modified the device by adding another pin-wheel and making the lugs moveable. This new machine was called Hagelin C-38 and it was much more secure compared to its predecessor.

In 1940 he brought to the US two copies of the hand operated C-38 and the Americans ordered 50 machines for evaluation. Once the devices were delivered, they underwent testing by the cryptologists of the Army’s Signal Intelligence Service and after approval it was adopted by the US armed forces for their midlevel traffic. Overall, more than 140.000 M-209’s were built for the US forces by the L.C. Smith and Corona Typewriters Company. (2) //

‘Report of interview with S/Sgt, Communications Section 79 Inf Div, 7th Army’. (dated March 1945) (51):

"The US Army code machine #209 was found to be something that hampered operations. It would take at least half hour to get a message through from the message center by use of this code machine and as a result the codes of particular importance or speed, for instance mortar messages, were sent in the clear."

Also, from the ‘Immediate report No. 126 (Combat Observations)’ - dated 6 May 1945 (52): ‘Information on the tactical situation is radioed or telephoned from the regiments to corps at hourly or more frequent intervals. Each officer observer averages about 30 messages per day.………………The M-209 converter proved too slow, cumbersome and inaccurate for transmission of those reports and was replaced by a simple prearranged message code with excellent results’.