Casey served as General of the Army Douglas MacArthur's chief engineer during the Battle of Bataan, in the jungles and mountains of New Guinea and the Philippines, and during the occupation of Japan. In the Battle of Leyte, he commanded the Army Support Command (ASCOM), which was responsible for all construction and logistics activities in the forward area. He hoped to become Chief of Engineers, but President Harry S. Truman passed him over. Later, Casey worked for Schenley Industries from 1951 until his retirement in 1965, and was chairman of the New York City Transit Authority from 1953 to 1955.