Between 1651 and 1654 a royalist rising took place in Scotland. Dunnottar Castle was the last stronghold to fall to the English Parliament's troops in May 1652. Under the terms of the Tender of Union, the Scots were given 30 seats in a united Parliament in London, with General Monck appointed as the military governor of Scotland. During the Interregnum, Scotland was kept under the military occupation of an English army under George Monck. Sporadic Royalist rebellions continued throughout the Commonwealth period in Scotland, particularly in western Highlands, where Alasdair MacColla had raised his forces in the 1640s. The north west Highlands was the scene of another pro-royalist uprising in 1653-55, which was only put down with deployment of 6,000 English troops there. Monck garrisoned forts all over the Highlands — for example at Inverness, and finally put an end to Royalist resistance when he began deporting prisoners to the West Indies as indentured labourers. However, lawlessness remained a problem, with bandits known as mosstroopers, very often former Royalist or Covenanter soldiers, plundering both the English troops and the civilian population. After the death of Oliver Cromwell in 1658, the factions and divisions which had struggled for supremacy during the early years of the interregnum reemerged. Monck, who had served Cromwell and the English Parliament throughout the civil wars, judged that his best interests and those of his country lay in the Restoration of Charles II. In 1660, he marched his troops south from Scotland to ensure the monarchy's reinstatement. Scotland's Parliament and legislative autonomy were restored under The Restoration though many issues that had led to the wars; religion, Scotland's form of government and the status of the Highlands, remained unresolved. After the Glorious Revolution of 1688, many more Scots would die over the same disputes in Jacobite rebellions.
Question: Who had raised his forces in the 1640s in western Highlands?
Answer: MacColla