The 2nd Battalion Royal Irish Fusiliers marched from their barracks at Winchester on 19th December 1914 to the docks at Southampton where they boarded the SS City of Benares. The following day they landed at Le Harve. Major Holmes took part in numerous engagements with the Battalion until 20th April 1915 when he was shot through the face by a sniper whilst the Battalion were located at Bellewarde Farm, during the second battle of Ypres. He was carried to an aid station, and was eventually transferred to Luddon Camp, Buncrana, County Donegal, Ireland, where, after enduring months of pain and suffering, he died of septic blood poisoning of the brain. He was later buried at Christ Church churchyard, Lower Fahan, Buncrana, where a memorial was erected to him, by the regiment. A fellow officer wrote about him "All the regiment past and present mourn with you; he was a perfect gentleman, a gallant soldier and a dear friend to all." He was mentioned in Field Marshall Sir John French's despatch published in the London Gazette on the 1st January 1916.