Junkers built marine diesels as early as 1913, two years before he
built his first aircraft. Through
World War I he concentrated on aero oil engines.
After the war Junkers switched to the development
of petrol engines and formed Junkers Motorenbau (Jumo) in
1923. Probably the most famous Jumo piston engines were the
V-12 211 and its derivative, the 213.
In 1936 Junkers Motorenbau merged with Junkers
Flugzeugwerke and began
developing a gas turbine engine. By 1939 the engine division had
a contract for development of an axial-flow turbojet. This
contract resulted in the Jumo 004 that powered the Me 262.