Background
He was son of Dermot O"Sullivan and nephew of Donal O"Sullivan Beare, Prince of Beare.
He was son of Dermot O"Sullivan and nephew of Donal O"Sullivan Beare, Prince of Beare.
The O"Sullivans, headed by the O"Sullivan Beare, owned much of Valentia Island in south-western Ireland. He served in the Spanish army. In 1621 he published his Catholic History of Ireland, a work not always reliable, but valuable for the Irish wars of the author"s own day.
He also wrote a Life of Saint Patrick, a confutation of Gerald of Wales and a reply to James Usher"s attack on his History.