Following the engagement at Fyvie Montrose's army fragmented, and Argyll, who had continued to pursue him, returned to Edinburgh, assuming that the arrival of winter would mean that the Royalist threat would disappear. However, towards the end of November, Montrose's major-general, Alasdair MacColla of the Clan MacDonald, who had not been at Fyvie because he had taken 500 men to relieve his Highland garrisons, rejoined Montrose at Blair Atholl with his Irish troops and up to 1,000 Highlanders (Reid 2003). Another source says that MacColla actually brought in 5,000 men (Sadler 1996), although Wishart only mentions that MacColla returned with the chief of Clanranald together with 500 of his men (Wishart 1893). Whilst it appears that Montrose wanted to take up winter quarters, MacColla, who, as a MacDonald shared a deep mutual enmity with the Campbell Duke of Argyll, persuaded Montrose to raid Inverary, the seat of Clan Campbell. Mild weather meant that the combined force was able to reach Inverary through the mountain passes, and, although the castle held out, the town was captured, and Argyll fled in his galley (Reid 2003). Montrose's forces ravaged Argyll's lands, 'an act of retaliation on Argyll, who had been the first of all to wage this cruel war of fire and sword upon his countrymen' (Wishart 1893).
Argyll then decided to retaliate in turn, seeking support from Lieutenant-General William Baillie, an experienced commander, who had just been recalled from England with his troops. Baillie rejected Argyll's plan to march into the highlands in pursuit of Montrose, because of the difficulty of supporting the army in winter conditions, and it was agreed that Baillie would base himself and his men at Perth, while Argyll pursued the Royalists, who were moving north into Lorne and Lochaber. The Royalists, as usual, were constantly losing men, and by the time they reached Kilchummin (now Fort Augustus) on 31 January 1645 Montrose had only 2,000 men. To add to his problems the Earl of Seaforth had reinforced the Inverness garrison at the north of the Great Glen, whilst Argyll was behind him at the south end in Inverlochy. Although there was an escape route over the Corrieyairack pass to Speyside, Montrose instead decided to go on the offensive and turn to attack Argyll (Reid 2003). It is possible that part of his motivation was that the lands of some of his key commanders, Keppoch, Lochiel, Glengarry and ClanRanald, were particularly threatened (Roberts 2000).
Avoiding the obvious route Montrose led a daring and arduous march through the midwinter hills with few provisions. The route took the Royalists due south up Glen Tarff as far as Culachy and then moved parallel to the Great Glen as far as Glen Buck, shielded by the long ridges of Meall a Cholumain and Druim Laragan. They then had to cross the gorge of the Calder Burn to reach the head of the glen, some 1,000 feet above sea level. From here they climbed another 1,000 feet to reach the col at Carn na Larach. Crossing the Teanga plateau they then descended steeply into Glen Turret and from there down Glen Roy to Keppoch, where they chased off one of Argyll's outposts, before crossing the Spean at Corriechoille, reaching Torlundy, overlooking Inverlochy, in the early hours of 2 February 1645. They arrived exhausted and hungry, having marched 36 miles in 36 hours (Reid 2003). 'The most part had not tasted bread these two days, marching over high mountains in knee-deep snow, wading brooks and rivers up to their girdle' (Patrick Gordon of Ruthven 1844). By this time the Covenanters were alerted and deployed for battle, having been alerted by those fleeing the outpost (Spalding 1851).
James Graham was the fifth Earl of Montrose and the first Marquis of Montrose. He was the chief of Clan Graham. Montrose had been a supporter and signatory of the National Covenant in 1638, but had then become a Royalist, although he was driven by motives other than a desire to impose the Divine Right of Kings upon Scotland. He and Archibald Campbell, the eighth Earl of Argyll, were bitter rivals, and Montrose believed that the Covenant had become nothing more than a vehicle for Argyll's ambition. Always a moderate among the Covenanters, Montrose considered that the agreement in 1641 with Charles that had removed episcopacy from Scotland had fulfilled the demands of the Covenant and that to continue in opposition to him would be breaking that agreement. Following the signing of the Solemn League and Covenant in September 1643, Montrose presented himself to Charles I service at his headquarters in Oxford. On behalf of the King, he then fought a campaign intended to draw Covenanter forces away from supporting the Parliamentarians in England, and in this it was a success. Montrose fought a series of seven battles against Covenanter armies across the Highlands in 1644 and 1645, beginning with Tippermuir and ending at Philiphaugh, where he suffered his only defeat He attempted to do the same on behalf of Charles II in 1650, but on this occasion fought only a single battle at Carbisdale. After his defeat there, he was captured and brought to Edinburgh for trial. On 21 May 1650, he was hanged and then beheaded. His head was fixed to a spike on Edinburgh's Tollbooth, his body quartered, and his limbs were displayed in Stirling, Glasgow, Perth and Aberdeen. Following the Restoration of Charles II as king in 1660, Montrose's remains were collected together once more and were interred in the High Kirk of St Giles in Edinburgh in May 1661.
Alasdair Mac Colla was the son of Coll 'Colkitto' MacDonald. He is widely credited with the creation of the 'Highland Charge', a tactic used with such devastating effect by Highlanders throughout the subsequent century, although some of the credit should likely also go to his compatriot Manus O' Cahan. He had fled to Ireland in 1638 to escape Campbell depredations in MacDonald territory within Scotland, and he fought for the MacDonnell Earl of Antrim in the Irish Rebellion of 1641. In 1644, he was dispatched to Scotland with between 1500 and 2000 Ulster and MacDonald troops to support Royalist efforts there, and to attempt to draw Covenanter forces out of Ireland and relieve pressure on the Irish Confederacy. Mac Colla gladly accepted the task, as Archibald Campbell, the Earl of Argyll, was not only the leading Covenanter in Scotland, he was also the clan chief of the Campbells, giving Mac Colla a chance to strike back against his hated foe. He landed in Argyll lands in July, immediately seizing the castle at Mingary. He continued to build his support in the north-west until he finally moved to Blair Atholl, where he joined his forces with Montrose at the end of August. This was the beginning of an immensely successful partnership, with Mac Colla present at the Royalist victories at Tippermuir, Aberdeen, Inverlochy, Auldearn and Kilsyth. However, Mac Colla's focus remained in his homelands in the north-west, so when Montrose moved south towards England, Mac Colla dispatched Manus O' Cahan with 700 of the Irish troops to go with Montrose while he returned to the north-west. After Montrose's defeat at Philiphaugh, Mac Colla continued to fight against the Campbells and the Covenanters in Scotland, with particular brutality displayed to any Campbells he encountered, until a concerted effort to defeat him in 1647 forced him to withdraw back to Ireland in May 1647. Later that year Mac Colla was serving in the Confederate Army of Munster when he was captured and shot at the Battle of Knocknanuss on 13 November.
Manus O'Cahan was the colonel of the Irish regiment that fought in all of Montrose's battles and which was the backbone of all his victories. He was a cousin of Mac Colla, and came over from Ireland with him. He and his regiment were sent to Scotland to ease pressure on the Irish Confederacy, who were fighting Scottish Covenanters and English Parliamentarians in Ireland. As Mac Colla had a recruiting role for the Royalist cause throughout 1644-5, he was occasionally absent in the west seeking fresh troops, but O'Cahan remained with Montrose throughout and was with Montrose for the Battle of Philiphaugh. He was captured after the defeat, his men were executed and he was taken to Edinburgh where he was hanged without trial. He was responsible for the invention of the Highland charge along with Mac Colla, although it is Mac Colla who is generally given sole credit.
Archibald Campbell, 1st Marquis of Argyll, was one of the leading Covenanters in Scotland. He had been opposed to Charles I's absolutism but had not been particularly in favour of Presbyterianism until 1638, when his refusal to support Charles led the King to send the MacDonnell Earl of Antrim to invade Argyll and raise the MacDonalds against the Marquis of Argyll. Although this was a failure, the Earl of Antrim was to later send his kinsmen Mac Colla and O'Cahan to support Montrose. Argyll became the most influential of the Covenanter lords, and was instrumental in the Solemn League and Covenant that sent Scottish Covenanters into England in support of the Parliamentarians. He was present at several of the battles fought by Montrose, being personally defeated by him at Fyvie and at Inverlochy, but was also the head of the Commission of Estates that had such a deleterious effect on Baillie at Alford and at Kilsyth. In later years, he led the Parliament that crowned Charles II as King of Scotland in 1651, but had lost control of events in Scotland and was reluctantly dragged into the invasion of England. He was imprisoned several times under the Protectorate for debt, and arrested for treason on the Restoration in 1660. He was cleared of any involvement in the execution of Charles I, but letters he had sent to Monck showed the extent of his cooperation with Cromwell and he was executed even before Charles had signed the death warrant.
In 1638 the National Covenant was signed by many in Scotland, pledging opposition to the reforms proposed by Charles I, the King of the two separate nations of England and Scotland. Amongst other proposals Charles wanted to replace the democratic Presbyterian system with a hierarchy of bishops and create a church modelled on High Anglican lines, and to finance his reforms by re-possessing the former land holdings of the Catholic Church which had been sold on at the Reformation and now formed the basis of many landowners' status and wealth. In 1639 and 1640 Charles was defeated in the two Bishop's Wars. Desperately short of finance, Charles was forced to recall the English Parliament, the so-called Long Parliament, and they reached a peace with the Covenanters in the Treaty of London in 1641. However, Charles and the English Parliament remained at odds over who should control the army, and the first English Civil War began in 1642. Initially the Royalists and the Parliamentarians were relatively evenly matched, and the Parliamentarians opened negotiations with the Covenanters for their assistance in breaking the deadlock. In 1643, under the terms of the Solemn League and Covenant, the Covenanter government of Scotland allied itself with the English Parliament and entered the war in England in early 1644, marking a major turning point in the war. Charles attempted unsuccessfully to foment rebellion in Scotland and the Scottish army went on to make a major impact in the campaign for the north of England. Following crushing defeat at Marston Moor on 2 July 1644 the King tried again, appointing James Graham, the 5th Earl of Montrose, as his military commander in Scotland. Montrose had been part of the abortive rebellion and was a former Covenanter himself who had joined the King in 1643. On 28 August 1644, Montrose raised the royal standard and embarked on a campaign against the Covenanter forces in the Highlands (Reid 2003).
Over the next two years, Montrose, with forces which changed constantly in size and composition, won a series of victories over the Covenanters under a number of different commanders, including: Tippermuir (1 September 1644), Aberdeen (13 September 1644), Inverlochy (2 February 1645), Auldearn (9 May 1645), Alford (2 July 1645) and Kilsyth (16 August 1645) and was elevated to 1st Marquis of Montrose by Charles as reward. However, he was defeated at Philiphaugh near Selkirk on 13 September 1645 by much superior Covenanter forces commanded by Lieutenant-General David Leslie. He endeavoured to carry on his campaign in the North-East, and also tried to threaten Glasgow, but lack of co-operation and poor relations between the leading Royalist commanders meant that they achieved little success and Montrose's campaign petered out in early May when his forces besieging Inverness were taken by surprise by Major-General Middleton's advance and fled without a fight. Although Huntly, another Royalist commander, stormed Aberdeen on 14 May, a few weeks later Charles, who had surrendered at Newark on 5 May, ordered his forces in Scotland to lay down their arms. Although Montrose was reluctant to do so, he finally disbanded his forces at Rattray on 30 July after agreeing terms with Middleton and then fled abroad (Reid 2003).