By 1911, Blair is boarding in house 9, Clonavon Terrace, Ballymena, Co. Antrim. He is described as an Accountant, Northern Bank.
He served with Coastal Defence; Defence of London; British Expeditionary Force and was later promoted to Flight Sergeant. Blair saw action at Messines 1917 and Ypres 1917. He was demobilised in January 1919 and was awarded the British Victory Medal and the British War Medal.