Born in 1671 at Loch Katrine, the third son of a Lieutenant-Colonel, MacGregor’s inherited long arms and great strength gave him abilities with the broadsword that made his name known to many. He fought at Killiecrankie for Viscount Dundee in 1689 before joining the Lennox Watch.
When the name MacGregor was again outlawed in 1694 he used his mother’s name of Campbell. His acquisitions of land and cattle brought him prosperity until 1711 when he persuaded a group led by the Duke of Montrose to advance him £1000.95 for investment in herding. His chief drover made off with the letters of credit, leaving MacGregor to face a charge of embezzlement. He did not answer to the charge or ensuing arrest warrant and was declared an outlaw.
He moved to the Trossachs lands of the Earl of Breadalbane, who was no friend of Montrose, and from there rustled cattle from Montrose’s lowland estates.