Malcolm held the position of 11th Chief of the Clan Chattan. In 1407 he obtained a lease for his life of the Barony of Moy, in Strathdearn, from John, Bishop of Moray. He fought in the Battle of Harlaw on 24 July 1411, for the King. He received a confirmation of the lands in Glen Royal and Glen Spean, also a grant of the heritable right of Stewardship of Lochaber. He held the office of Constable of the castle of Inverness in 1428, appointed by King James I, which he then defended during the same year against Alexander, Earl of Ross.
In 1442 he and his clan were invited to a feast at the Castle Rait by the Comyns. Although the Comyns offered reconciliation with the Mackintoshes, they secretly sought revenge for having been defeated some years previously. However a Comyn lad, in love with a Mackintosh lass, told her that when a boar's head was borne into the feast this would be a signal for the attack of the Comyns. She revealed the plot, and immediately when the boar's head appeared, the Mackintoshes fell on the Comyns and slaughtered them, regaining the Castle of Rait, which together with the Meikle Geddes, also regained in 1442, had been in the Comyn family for 100 years.
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