Catholic Irish rebels who had massacred Scottish settlers in Ulster during the Irish Rebellion of 1641. Monro's campaign in Ireland was largely confined to the northern province of Ulster. After taking and plundering Newry in April 1642, and ineffectually attempting to subdue Sir Phelim O'Neill, Monro succeeded in taking prisoner the Earl of Antrim who was Randal MacDonnell, 1st Marquess of Antrim at Dunluce Castle. The arrival of Owen Roe O'Neill in Ireland strengthened the cause of the rebels, now organised in Confederate Ireland, and Monro, who was poorly supplied with provisions and war materials, showed little activity. Moreover, the English Civil War was now creating confusion among parties in Ireland, and the king was anxious to come to terms with the Catholic rebels, and to enlist them on his own behalf against the parliament. The Earl of Ormonde, Charles's lieutenant-general in Ireland, acting on the king's orders, signed a cessation of hostilities with the Catholic Confederates on 15 September 1643, and exerted himself to despatch aid to Charles in England. Conflict in Ulster Monro's strategy was just as ruthless and no measure was spared in his campaign against O'Neill. The conflict led to thousands of innocent people being killed on both sides. O'Neil waged a guerilla-type offensive in Ulster, whereas Monro, superior in numbers systematically destroyed castles and villages throughout the land. Some accounts tell of him laying waste to Antrim and Down in what we would now call a "scorched earth policy". Monro attacked and took Newry in 1642 and took Belfast in 1644. After taking Newry Robert Monro then raised the Siege of Coleraine, a town which later became the centre of military activities and the headquarters of Major Daniel Munro during the coming years. Belfast is seized Monro in Ulster, holding his commission from the Parliament of Scotland dominated by the Covenanters, did not recognize the armistice, and his troops accepted the Solemn League and Covenant, in which they were joined by many English soldiers who left Ormonde to join him. In April 1644 the English parliament entrusted Monro with the command of all the forces in Ulster, both English and Scots. He thereupon seized Belfast, made a raid into the Pale, and unsuccessfully attempted to gain possession of Dundalk and Drogheda. In response, the Irish confederates sent an armed expedition to Scotland to join the Scottish Royalists there under James Graham, 1st Marquess of Montrose.