Education
He was educated at Royal Belfast Academical Institution and Queen"s University Belfast.
He was educated at Royal Belfast Academical Institution and Queen"s University Belfast.
In 1930 he went to the Institute of Historical Research in London, and graduated with a Doctor of Philosophy in 1934. He was Professor of Modern History at Trinity College, Dublin, from 1940 to 1977, when he became professor emeritus. With Robert Dudley Edwards, he founded Irish Historical Studies and The Irish Committee of Historical Sciences and began publication of A New History of Ireland.
In the 1930s he.