Doughboy
The word "doughboy" was well known almost 100 years before World War I in Britain and America. Doughboy had a different meaning then. Soldiers in Spain, America, and Britain were all familiar with fried doughnuts called doughboys. Because of the occasional contact of the nation's armed force and transatlantic migration, it seems likely that this usage was known to the members of the U.S. Army by the early 19th century.