Herbert enlisted on 30th November 1905. He entered the war in France on 13th August 1914, as part of the Regimental Medical Officer's team for the 2nd Bn. Royal Munster Fusiliers. On 23rd November 1914 the Medical Officer of the Royal Munster Fusiliers reported Hebert had done good work resulting in him being given the acting rank of Corporal, and they asked the A.D.M.S. for pay for the rank to be forwarded. He was discharged unfit on 30th May 1917.