Complex sentence: In the early 1930s, the U.S. Army ordered the development of an amphibious observation plane, designated the Douglas YO-44, based on the U.S. Navy's XP3D-1 seaplane.
Split into simpler sentences: In the early 1930s, the U.S. Army began developing an amphibious observation plane, designated the YO-44. The YO-44 was based on the U.S. Navy XP3D-1 seaplane.