The unit was mustered into federal active service on 16 July 1917 for service in World War I, and Rickards remained its commander. On 11 October 1917 the 16th Pennsylvania Regiment was redesignated as the 112th Infantry Regiment and became part of the 28th Infantry Division. The 112th was the first war-strength National Guard regiment in the United States. The regiment reached France in May 1918 as part of the American Expeditionary Force. It went onto the line on 4 July 1918, in the Second Battle of the Marne. From that day on, the names Fismes, Fismette, Fond de Mezieres, and Argonne would never be forgotten. The second battalion's Companies G and H lost a combined total of 200 men out of 230 when they were cut off at Fismette and fended off a frontal attack on their position by a thousand German soldiers. The 112th Infantry Regiment returned home in April 1919 and was mustered out of federal service on 6 May 1919 at Camp Dix, New Jersey. The regiment was awarded battle streamers marked Champagne 1918, Champagne-Marne, Aisne-Marne, Oise-Marne, Lorraine 1918, and Meuse-Argonne for its service in France.