Gilbert enlisted on 28th October 1914. He was a metal designer by trade. He entered the war in France on 16th April 1915, joining the 2nd Field Ambulance in the field. In a memo dated 26th June 1915 the Deputy Director of Medical Services, 1st Division, wrote in a memo that he wished to bring to notice the names of men, who under the guidance of the officers commanding bearers of No 1 & 2 Field Ambulances advanced in front of their new line on the night of the 18th May 1915 and under shell fire succeeded in bringing in 3 wounded to the trench - Gilbert was on the list of names. On 18th September 1918 he was at an Advances Dressing Station when he became wounded by a mustard gas shell. He was taken to No 1 American General Hospital where he was treated for blindness for 5 days. On 17th May 1919 he was transferred to Class Z Army Reserve on demobilization.