Cahir had a strong claim to succeed as chief of the O'Doherty's, the dominant clan on Inishowen.
Because of this he was captured by Red Hugh O'Donnell, who supported a rival candidate.
They had previously sided with the rebels during the Nine Years War, with Hugh Boy making a failed attempt to capture Culmore Fort.
[1] They now switched to support the Crown and allied themselves to Sir Henry Docwra, the English Governor of Derry.
He was later praised by Docwra as "a man whom I found faithful and honest".