After two and a half years of fighting, a truce was agreed on 11 July 1921. When the Dáil approved the Anglo-Irish Treaty, in January 1922, the IRA split into pro- and anti-treaty camps. Over the coming months and after being elected onto the army’s executive as Adjutant-General, O'Donoghue warned of the dangers of an Irish Civil War. In June 1922, he resigned from the army's national executive and a month later, on 3 July 1922, from the army. Civil war did break out on June 28, 1922 between pro and anti treaty factions, much to O'Donoghue's dismay.