m. 21 Apr 1225
Facts and Events
Sir William Óg was the third son of Richard Mor de Burgh, Lord of Connacht. De Burgh served with distinction in France with King Henry III in 1245 and later in Scotland. He was involved in fierce feudal warfare in Ireland where he killed the Lord of Desmond. He was killed at the Battle of Áth an Chip or Athankip by the Ua Conchobair Kings of Connacht, in 1270.
He was survived by at least one son, Sir William Liath de Burgh, Custos or of Ireland, who married Una, a daughter of the Mac Jordan of Connacht, and died in 1324. William Óg was thus ancestor the Mac William Iochtar, the Bourkes of County Mayo.