He entered the United States Military Academy (USMA) at West Point, New York in June 1913, from where he graduated 53rd in a class of 139 on April 20, 1917, exactly two weeks after the American entry into World War I, as a second lieutenant of Infantry.

That month saw Irving move on again, now to the 15th Machine Gun Battalion, also part of the 5th Division, with which he would remain for the rest of the war, again taking command of a company.

[1] Along with the rest of the 5th Division, Irving departed for service on the Western Front to join the American Expeditionary Forces (AEF) in the spring of 1918.

[1] After arriving in France, Irving, after holding the line with his battalion for several weeks, went on to see action in the St. Mihiel offensive in September.

[2] He was wounded during the battle and subsequently received the Silver Star for "leading his company through heavy artillery and machine gun fire.