The Clandeboye massacre in 1574 was a massacre of the O'Neills of Lower Clandeboye by the English forces of The 1st Earl of Essex. It took place during an attempted English colonisation of Ulster as part of the Tudor conquest of Ireland. The Lord of Lower Clandeboye, Sir Brian McPhelim O'Neill, had violently opposed these attempts at colonisation. O'Neill would invite Lord Essex to parley at his castle in Belfast; however, at the end of the feast, the English forces turned on the O'Neills and killed up to 200 of them including women and children. Essex ordered that O'Neill, his wife and brother to be seized and executed for treason and for opposing the plantations.