The Harley-Davidson WLA motorcycle was nicknamed the 'Liberator' because it was used by U.S. soldiers liberating occupied Europe. Harley-Davidson began producing the WLA for the U.S. military in 1940, later entry of the United States into World War II saw significantly increased production, with over 90,000 being produced during the war. The US Army motorcycles were used for police and escort work, courier duties and scouting. They were almost never used as combat vehicles or troop mobility, it was a single-rider design and rarely equipped with sidecars commonly found on the German motorcycles.
According to Wikipedia the model designation breaks down as follows: