The second surviving son of Edward III of England and Philippa of Hainault, known as Lionel of Antwerp from his birth in Antwerp. From about 1341 it was arranged that he would marry the Anglo-Irish heiress Elizabeth de Burgh (1332–63); he was created Earl of Ulster and in 1361 was sent to Ireland as governor, to reassert English rule there. In 1362 he was created Duke of Clarence, the title being derived from his wife’s inheritance of the lordship of Clare in Suffolk. After her death another rich marriage was arranged for him, to Violante, the only daughter of Galeazzo Visconti, Lord of Pavia; he died only a few months after this wedding.

The title of Clarence was revived in 1412 for Thomas of Lancaster (1389–1421), second son of Henry IV and Mary de Bohun; it lapsed again after his death.