Background
He was the youngest son of Conn O'Donnell, and grandson of Calvagh O'Donnell who had ruled the O'Donnell lands of Tyrconnell.
He was the youngest son of Conn O'Donnell, and grandson of Calvagh O'Donnell who had ruled the O'Donnell lands of Tyrconnell.
Conn and two other brothers, Hugh Boy and Donal also defected bringing with them as many as a thousand warriors by some estimates. They assisted the Crown's capture of Lifford, a key O'Donnell stronghold, to the outrage of Hugh Roe who killed Niall Garve's young son (and Conn's nephew) in retaliation. Conn played an active role in the fight against Hugh Roe, most notably during the Siege of Donegal in 1601.
It was a lengthy and hard-fought conflict during which Donegal Abbey was wrecked by the explosion of barrels of gunpowder which had been stored there. During the fighting Conn was fatally wounded.