After entering the Army on 6 Apr 1918, Harley was assigned first to 6th Company of the Training Battalion of the 58th Dep Brigade. On 3 May 1918 he was transferred to Headquarters and Headquarters Company 331st Infantry. He was then assigned to 3rd Army Corps and the Provisional Replacement Battalion of 7 AC. On 16 Sep 1918 PVT Derrough was transferred to Headquarters and Headquarters Company 116th Infantry. PVT Derrough was killed in action on 27 Oct 1918.
PVT Derrough was repatriated in 1921 and re-interred in Arlington National Cemetery in Arlington, Virginia.