As soon as World War I began in August 1914, Wilson enlisted. He served in the Royal Army Medical Corps from 1914 to 1915, first as a stretcher-bearer then later as a Chaplain in the disastrous Gallipoli Campaign of 1915. After serving with the Royal Army Medical Corps, Wilson entered the Royal Army Service Corps then, from 1916 to 1919, he served as a chaplain in the Royal Armed Forces. He was mentioned in dispatches and awarded the military O.B.E. for his part in evacuating people from an airfield in France. He received a letter signed by Winston Churchill.
Marriage
Wilson married the widow of his friend who had died during WWI in 1915. Wilson married Ella Lee in 1920 and went to live in St Andrews after he was appointed rector of All Saints by his former vicar and by then Dean of St Ninian's Cathedral in Perth, Patrick Smythe.