General William Hood Simpson was a senior United States Army officer who served with distinction in both World War I and World War II. He is best known for being the Commanding General of the Ninth United States Army in northwest Europe during World War II.
A graduate of the United States Military Academy at West Point, New York, where he was ranked 101st out of 103 in the class of 1909, Simpson served in the Philippines, where he participated in suppression of the Moro Rebellion, and in Mexico with the Pancho Villa Expedition in 1916. During World War I he saw active service in the Meuse-Argonne Offensive on the Western Front on the staff of the 33rd Division, for which he was awarded the Army Distinguished Service Medal and Silver Citation Star. Between the wars he served on staff postings, attended the Command and General Staff College and the Army War College, and commanded the 3rd Battalion, 12th Infantry Regiment.
During World War II he commanded the 9th Infantry Regiment and was the assistant division commander of the 2nd Infantry Division. In succession he commanded the 35th and the 30th Infantry Divisions, the XII Corps, and the Fourth Army.