Sir William Óg de Burgh, Anglo-Irish noble and soldier, died 1270. 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.