 Returning to the United States in July 1920, Somervell was posted to the Office of the Chief of Engineers in Washington, D.C. His war record earned him a place at the Command and General Staff College at Fort Leavenworth, reserved for the Army's best and most promising officers.He once again ranked near the top of his class.After graduation he was posted to the 1st New York Engineer District but soon obtained leave to assist Hines with a special study of navigation on the Rhine and Danube Rivers on behalf of the League of Nations, essentially a continuation of the work that the two men had done in 1920.