All Americans were encouraged to support World War 2 in any way they could. The government even resorted to using propaganda to increase support for the allies, though it never reached the level of intensity as World War 1. Harley Davidson supported the war effort by producing an Army spec of the civilian WL model. In 1940, the Harley Davidson WLA began production.
Late entry into World War 2 increased production of the WLA and motorcycles used during the war have serial numbers indicating a manufactured date of 1942. They are known as 42WLAs. WLA is a model designation code: W indicating use of the 45ci flathead, L meaning high compression and A for Army specification. Production would cease after World War 2, but began for the Korean War from 1949 to 1952.
Aside from an olive drab/military paint scheme, other changes included blackout lights for nighttime secrecy, modified fenders to shed mud more efficiently, a skid plate and a heavy-duty luggage rack.
The WLA were almost never used for combat, but were used for police, courier and scouting duties. It became known as the "Liberator."