Artillery observation and liaison among friendly forces were the earliest roles for military aircraft. Building upon their experience in WWI, the U.S. Army Air Corps ordered a series of observation aircraft during the 1920s and 1930s. These aircraft grew larger in size, which made them harder to operate in the field. The German Fieseler Fi 156 Storch made a great impression on USAAC officers who saw it demonstrated in 1938. This lead to several U.S. manufacturers offering light aircraft suitable for observation and liaison missions from front-line airfields. The liaisons began with the Stinson L-1 (formerly O-56), which began production in 1940. Evaluation during 1941 maneuvers in the southern U.S. led the Army to select the Taylorcraft L-2 (O-57), the Aeronca L-3 (O-58), and the Piper L-4 (O-59). Finally, Stinson’s L-5, (O-62) entered service in 1942. These liaison aircraft saw extensive service on all fronts with the U.S. forces during WWII. The L-4 and L-5 served during the Korean War, too.