On 9 August 1915, MacRory was appointed
Bishop of Down and Connor by
Pope Benedict XV and received his
episcopal consecration on 14 November from
Michael Cardinal Logue. He chose as his episcopal
motto Fortis in Fide ("Strong in Faith"). From 1917-18, he was one of the four clerical members of the
Irish Convention and said, in a letter to the Rector of the
Pontifical Irish College that he was attending in order to oppose partition "with all my heart." He was one of the delegates who backed the option of full
Dominion Status for Ireland.
Sir Horace Plunkett, who chaired the convention, recorded in his diary that, in August 1917, Bishop MacRory made a bad speech "raking up the past." During
The Troubles in Ulster (1920–1922) Bishop MacRory proposed that the overwhelmingly Protestant paramilitary police force the
Ulster Special Constabulary be disbanded and a new force established (made up of 50% Catholics). ==Archbishop of Armagh==