When Royalist hopes of uniting Ireland behind Charles II ended with Cromwell's Irish campaign in 1649, Charles turned his attention to Scotland. Earlier negotiations with the Covenanters for military support against the Commonwealth had broken down but by the end of 1649 Charles was left with no option but to seek another treaty. At the same time, he appointed the Marquis of Montrose his Captain-General and commissioned him to raise forces for an invasion of Scotland. Montrose was passionately loyal to the Royalist cause and had been an avowed enemy of the Covenanters since his spectacular campaign against them for Charles I in 1644-5. Charles II planned to use the threat of another campaign by Montrose to coerce the Covenanters.
During the spring of 1649, Montrose travelled through Scandinavia, the German states and Poland attempting to raise troops, supplies and money for the Royalist cause, but with little success. Negotiations between Charles and the Covenanter leaders broke down in May 1649 and Montrose was authorised to take military action against them with whatever forces he could raise. In September 1649, he sent 200 Danish mercenaries under the command of the elderly Earl of Kinnoul as an advance guard to occupy Kirkwall, the main town on Orkney, while he tried to raise further support in Germany.
On 23 March 1650, Montrose himself landed at Kirkwall with around 250 German mercenaries and a small supply of weapons. Montrose's lieutenant-general Lord Eythin remained on the continent with orders to organise a second wave of mercenaries. Montrose was accompanied by his former adversary Sir John Hurry whom he had defeated at the battle of Auldearn in 1645 but who had now changed sides and become Montrose's major-general. Around 1,000 local Orcadians had been recruited to the cause, though the sudden death of the Earl of Kinnoul meant that they had received little training. Upon his arrival on Orkney, Montrose received a letter from Charles informing him that he was to be rewarded with the Order of the Garter, and also that Charles intended to begin a further round of negotiations with the Covenanters at Breda. Montrose was expected to threaten the Covenanters while Charles negotiated with them, but Montrose regarded an alliance between the King and the Covenanters as a potentially disastrous policy. He therefore set out to emulate the campaign he had led in 1644 to raise Scotland for the King.
On 9 April 1650, Montrose sent Major-General Hurry across the Pentland Firth with an advance party to secure a route south. Montrose followed with his main force and occupied Thurso where he declared his mission. On 17 April, Montrose summoned Dunbeath Castle in Caithness, which surrendered four days later. Leaving a small garrison at Dunbeath, Montrose marched through Sutherland towards Dunrobin Castle, seat of the earls of Sutherland. Dunrobin was too strong to assault and it soon became clear that there was little local support for the Royalist cause. The Monro, Ross and Mackenzie clans, which Montrose expected to join him, sided with the Covenanters. Meanwhile, Lieutenant-General Leslie mustered his forces at Brechin in Angus and prepared to march against Montrose. Lieutenant-Colonel Archibald Strachan led Leslie's advance guard of cavalry to Inverness.
From Dunrobin, Montrose turned inland and marched along the valley of the River Fleet to Lairg where he tried to raise support before turning south to Carbisdale. Behind him, the covenanting Earl of Sutherland advanced to cut off the route back to the north, while Lieutenant-Colonel Strachan moved swiftly up from the south.
On 27 April 1650, Montrose's force of 1,200 foot and 40 cavalry took up a strong position on the lower slopes of Carbisdale. Montrose's camp was protected by earthworks and Strachan was heavily outnumbered, having only 200 Covenanter horse, a few musketeers and 400 unreliable Highlanders of the Ross and Monro clans. In the hope of luring the Royalists down from their strong position, Strachan concealed most of his forces in a deep gully, allowing only one company of horse to be seen by Montrose. Assuming that this was all he had to face, Montrose moved forward to give battle. As soon as the Royalists left the protection of the hill, Strachan attacked with the full force of his hidden cavalry. Montrose's Orcadian recruits fled without offering any resistance. The Danish and German mercenaries fell back to the hillside and were attacked and routed by the Monro and Ross Highlanders. Montrose's small force of cavalry fought bravely but was soon overwhelmed. Colonel Hurry was taken prisoner; Montrose himself escaped from the battlefield but was betrayed to the Covenanters a few days later. Both Hurry and Montrose were executed as traitors in Edinburgh the following month.
Charles had written to Montrose ordering him to abandon the invasion and disarm his troops because formal negotiations with the Covenanters had begun. The order was sent too late. The King subsequently disavowed Montrose under the terms of the Treaty of Breda, signed on 1 May 1650, in order to secure an alliance with the Covenanters.
References:
S.R. Gardiner, History of the Commonwealth and Protectorate vol. i, 1903
Peter Gaunt, The Cromwellian Gazetteer, 1987
David Stevenson, Revolution & Counter-Revolution in Scotland 1644-51, 1977