He was not, however, able to hold Perth; many of the Highlanders forming his army immediately returned home with their plunder and a stronger government force under the Marquess of Argyll was approaching the town from the west.

With around 1,500 Irish infantry under Alasdair MacColla, a small number of Keppoch clansmen and around 80 horse, Montrose made a rapid advance, but found another government army blocking his path outside Aberdeen.

[4] There were also at least three troops of regular cavalry, commanded by Captain Alexander Keith, Sir William Forbes of Craigevar and Lord Lewis Gordon, along with further untrained 'fencibles'; government horse totalled around 300.

His left wing, under the professional soldier Colonel James Hay, included Gordon's cavalry and a small unit of Irish musketeers led by Captain Mortimer of O'Cahan's regiment.

The right wing, commanded by Sir William Rollo, included Ogilvie's troopers and a number of Highland infantry; the centre was made up of the Irish under Mac Colla.

The Aberdeen Militia gave way before a final "Highland charge" and fled into the town, pursued by Laghtnan's men, beginning a general retreat of the government forces.

Goods were looted, women raped, and at least 118 (according to Spalding) and perhaps as many as 160 (according to Alexander Jaffray, who was also at the battle)[8] people were killed, including three members of the town council and a large number of tradesmen and ordinary residents.

[6] Spalding recorded that the townspeople eventually took to wearing a twist of oats in their bonnets, the Royalists' badge, in an attempt to deflect the attentions of the marauding troops.

Montrose remained in Aberdeen for three days, before leaving for Rothiemurchus in the Highlands to recruit new men and avoid a confrontation with the approaching Parliamentarian force under the Marquess of Argyll.

A highly partial version of the sack of Aberdeen and a more accurate portrayal of the Royalist campaign of 1644–1645 is featured in the 1937 novel And No Quarter by the Irish writer Maurice Walsh, told from the perspective of two members of O'Cahan's Regiment.