J.A.F. Gregg, Church of Ireland Archbishop of Armagh, played an important role in religious life across the island of Ireland for half of the twentieth century. He has been portrayed by historians as the “Marble Arch,” a leader who reigned over one Church across two states. This article reevaluates that interpretation: by using the period of the Second World War as a case study, it suggests that the historiographical portrayal of Gregg has neglected other significant aspects of his character and career. This article contends that, in addition to being a dominant leader, he was a British patriot, a pastor, and a scholar. Gregg navigated a course that recognized both states and their differing positions regarding the conflict; and he contributed to post-war desires for unity among Irish Anglicans across those states during a period of increased division on the island. The article, by bringing fresh attention to Gregg, discusses an under-examined figure in the history of the Church of Ireland and explores a hitherto neglected period in that historiography. By contextualizing Gregg's wartime rhetoric with that of Anglican churchmen in England, the study also addresses lacunae both in the historiography of religion and the Second World War and in that of Irish and Northern Irish experiences of the conflict.