Editing Enigma machine (section)

==== Wehrmacht Enigma I (1930–1938) ====
Enigma machine G was modified to the ''Enigma I'' by June 1930.{{sfn|Kruh|Deavours|2002|p=97}} Enigma I is also known as the ''Wehrmacht'', or "Services" Enigma, and was used extensively by German military services and other government organisations (such as the [[Deutsche Reichsbahn#Deutsche Reichsbahn-Gesellschaft (1924-1937)|railways]]{{sfn|Smith|2000|p= 73}}) before and during [[World War II]].

[[File:Bundesarchiv Bild 101I-769-0229-10A, Frankreich, Guderian, "Enigma" cropped.jpg|thumb|upright|[[Heinz Guderian]] in the [[Battle of France]], with an Enigma machine. Note one soldier is keying in text while another writes down the results.]]
The major difference between ''Enigma I'' (German Army version from 1930), and commercial Enigma models was the addition of a plugboard to swap pairs of letters, greatly increasing cryptographic strength.

Other differences included the use of a fixed reflector and the relocation of the stepping notches from the rotor body to the movable letter rings. The machine measured {{convert|28|x|34|x|15|cm|in|abbr=on}} and weighed around {{convert|12|kg|lb|abbr=on}}.{{sfn|Stripp|1993|p=83}}

In August 1935, the Air Force introduced the Wehrmacht Enigma for their communications.{{sfn|Kruh|Deavours|2002|p=97}}