America's greatest technological contribution during WWI was the Liberty 12-cylinder water-cooled engine. Rated at 410 hp., it weighed only two pounds per horsepower, far surpassing similar types of engines mass-produced by England, France, Italy, and Germany at that time.

During the war, 20,478 Liberty 12s were produced by Packard, Lincoln, Ford, General Motors , Nordyke, and Marmon. They were used primarily in U.S.-built D.H.4s, the only American-made airplane to get into combat over the Western Front.