 He inherited the earldom in 1614 because his uncle Thomas ("Black Tom" or "Tomás Dubh") had died without legitimate male issue.Following the failure of the senior line, Walter's Kilcash branch would supply five earls of Ormond.He married his second cousin, Helen Butler (also known as Ellen), daughter of Edmund Butler, 2nd Viscount Mountgarret and Grizel FitzPatrick.