Several O'Dowds were bishops of the see of Killala. Father John Ó Duada, who was tortured and hanged in 1579, was one of the many Irish Franciscan martyrs. Many of the name appear in the ranks of the Confederate Catholics and, later in the seventeenth century, in Catholic King James II of England's army during the Williamite war in Ireland (1688–1691). The head of the sept at that time, who was killed at the Battle of the Boyne (1690), is said to have been seven feet tall.