Probably the earliest authentic history of Mackintosh is traceable to Shaw or Seach MacDuff, a Cadet son of the third Earl of Fife. The son of MacDuff, for his support of Malcom IV, was awarded the lands of Petty and Breachley in Invernesshire and was appointed Constable of the Castle thereto. Assuming the name "Mac-an-toisch", which means "Son of the Thane or Chief", he began his own Clan. The Clan support of James I in 1429 resulted in large tracts of land being settled on the Mackintoshes. Clan Mackintosh was involved in the "Battle of the Thirty", a mass trial by combat, which was held under the judicial control of the King in 1396 on the North Inch of Perth, in which Clan Macintosh regained all lands taken from the Shaws.

Clan Mackintosh supported the King in the revolt of 1688, but in 1715, Mackintosh gave his support to the Jacobite Rebellion. At the "45 Rising", Angus, who held a commission in the Black Watch, could not in honor raise the Clan for Prince Charles Edward. His wife, Lady Ann (Colonel Anne), raised the Mackintosh Battalions for Clan Chattan in support of "Bonnie Prince Charlie". The Chattan Regiment distinguished itself at the Battle of Culloden under the leadership of the Chief of the MacGillivray's and was one of only two Scottish Regiments which did not lose their colors. Earlier, following "Colonel Anne's" tactics, five Mackintoshes, under the leadership of Frasier, the Blacksmith, had routed 1500 of Lord Louden's Troops who were approaching Moy Hall in an attempt to capture Bonnie Prince Charlie.

Clan Mackintosh is second to none. It's members have demonstrated that they are stalwart, fearless, and adventuresome people. In the United States, Mackintoshes have played an important part in it's history, especially in the Southeast. A group under John Mor Mackintosh helped guard General Oglethorpe's new colony in Savannah, Georgia and aided in extending settlements west to the Tombigbee River between Georgia and Arkansas. The Clan Mackintosh spirit is as strong as ever and binds our clansmen together in all parts of the world.