Complex sentence: Soon after the United States entered the war, the War Department decided to deploy Major General Carl Spaatz's Eighth Air Force to Britain, putting the North Atlantic ferry route facilities constructed by the Corps to an early test.
Split into simpler sentences: Soon after the United States entered the war, the War Department decided to deploy Major General Carl Spaatz's Eighth Air Force to Britain. This put the North Atlantic facilities constructed by the Corps to an early test.