Bromley entered the war in France on 29th October 1914. On 6th June 1917 he joined the 141st Field Ambulance for duty from the 2nd Bn. Royal Sussex Regiment. He received notice that he would be awarded the Military Medal on 13th October 1918. On 8th December 1918 he proceeded to Transportation Troops Base Depot for duty and was accordingly taken off the strength of the unit.