Lt. Albert F. Ward, who was killed in action at Novitskaya, Siberia on June 22, 1919. Photo was taken from his yearbook. He was in the June 1918 class at West Point and was the only American officer killed in the American Intervention. He was with the 31st Infantry and was leading a rescue party to free four American soldiers captured by the Bolsheviks when he was killed. 

Photo courtesy of the US Military Academy Museum at West Point.

Thanks to Robert Willett for the information about Lt. Ward