Catherine O’Neill

The custom among the nobility of sixteenth-century Ireland was for marriage to be undertaken to cement political alliances between powerful or enemy families. If the alliance fell apart, the wife could return to her father in a form of political divorce. All Shane's marriages were of this type. His first wife was Catherine, the daughter of James MacDonald of Dunnyveg, Lord of the Isles. The O'Neill married Catherine while the MacDonnells were providing him with military support during the 1550s to contest the Lordship of Tyrone with his father Conn Bacach, at the time the O'Neill.

The O'Neill divorced Catherine to forge an alliance with the O'Donnells of Tyrconnell. He married Mary, a daughter of the Lord of Tyrconnell, Calvagh O'Donnell. Mary's brother's open hostility to the alliance led to the O'Neill rejecting Mary. In the ensuing conflict, the O'Neill captured and imprisoned her father Calvagh O'Donnell.

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