Richard Óg was the most powerful of the de Burgh Earls of Ulster, succeeding his father in Ulster and Connacht upon reaching his majority in 1280. He was a friend of King Edward I of England, and ranked first among the Earls of Ireland. Richard married Margaret, the daughter of his cousin John de Borough and Cecily Baillol. He pursued expansionist policies that often left him at odds with fellow Norman lords.
His daughter Elizabeth was to become the second wife of King Robert the Bruce of Scotland. However, this did not stop him leading his forces from Ireland to support England's King Edward I in his Scottish campaigns and when the forces of Edward Bruce invaded Ulster in 1315, the Earl led a force against him, but was beaten at Connor in Antrim. The invasion of Bruce and the uprising of Felim Ó Conchúir in Connacht left him virtually without authority in his lands, but Ó Conchúir was killed in 1316 at the Second Battle of Athenry, and he was able to recover Ulster after the defeat of Bruce at Faughart (wikipedia)