From the longer Wikipedia page 
John of Islay (or John MacDonald) (1434–1503) was a late medieval Scottish magnate. He was Earl of Ross and the 4th Lord of the Isles as well as being Mac Domhnaill, chief of Clan Donald. John would however prove to be the last of the Lords of the Isles, overmighty subjects of the Stewart Kings of Scotland and virtual kings in their own right in the Western Isles. His struggle for power with King James III of Scotland ended in humiliation, following which his illegitimate son Angus Óg rebelled against his rule. In a bitter civil war, John's fleet of galleys met those of Angus sometime in the early 1480s off the coast of Mull at the Battle of Bloody Bay, in which John's cause was defeated. After Bloody Bay he became an inconsequential figure; and Angus continued to dominate the affairs of Clan Donald up until his murder in 1490. In 1493 James IV brought the Lordship of the Isles to an end. John died unlamented in 1503, having witnessed the almost complete destruction of his family inheritance.