sentences:  He was a younger son of Aonghus Mór mac Domhnaill, Lord of Islay.After the latter's apparent death, the chiefship of the kindred was assumed by Aonghus Óg's elder brother, Alasdair Óg Mac Domhnaill.Most of the documentation regarding Aonghus Óg's career concerns his support of Edward I, King of England against supporters of John, King of Scotland.