Campbell was educated at Lisburn School and at Belfast University, where he graduated M.B., B.Ch., and B.A.O. in 1914. He took a commission as Lieutenant in the R.A.M.C. Special Reserve on 5th February 1914. He joined for duty on 7th August 1914, entering the war in France with No 1 General Hospital on the 20th. On 6th September 1914 he was instructed by the Assistant Director of Medical Services (A.D.M.S.), No III Base to proceed to Le Mans and report for duty to the A.D.M.S. there. On 28th February 1915 he arrived for temporary duty with the 15th Field Ambulance, “B” Section in place of another officer going on special leave to England. He was promoted to the rank of temporary Captain on 1st April 1915, then on 1st January 1917 took a permanent regular army commission at the rank of Lieutenant (temporary Captain). He became Captain on 6th February 1918 but was acting under the rank Major from 4th January the same year. He was awarded the Military Cross "For conspicuous gallantry and devotion to duty during operations. He directed the stretcher-bearers under heavy shellfire with the greatest coolness and courage. He succeeded in entering a village which had been heavily shelled and with another captain, a sergeant and four men collected the wounded into a dug-out and succeeded in getting them back later. He has frequently showed great courage." The unit had set up the Main Dressing Station at Bus when a high velocity shell landed directly on a small shelter (dug out) where he and Capt (a.Lt/Col) Frederick Hoysted Bradley were sleeping - they were both killed. The Bar to his Military Cross was gazetted after his death, "For conspicuous gallantry and devotion to duty. During an important engagement he organised the evacuation of the wounded with great skill and devotion to duty, proceeding frequently himself in charge of bearers, though heavy shelling, to the rear aid posts. It was largely due to his able organisation and fine example of self-sacrificing gallantry that the numerous casualties were evacuated so expeditiously." He was awarded the 2nd Bar "During various attacks this officer supervised the collecting of wounded over a large part of the divisional front. He closely followed the advancing troops with his stretcher-bearers, evacuating the wounded skillfully and speedily. On one occasion during a retirement he personally under heavy fire reconnoitered the ground where the wounded lay, and by his dispositions of the stretcher-bearers undoubtedly saved their lives and the lives of many of the wounded." Campbell was the youngest son of Mr William McCormack of Hillhall House, Lisburn.