The dispute reached back to before 1291, when the lands at Loch Arkaig had belonged to Dougal Dall MacGilleCattan, chief of the ancient Clan Chattan. That year his daughter Eva married Angus Mackintosh, sixth chief of Clan Mackintosh, and the two clans united in what became the Chattan Confederation. The Mackintoshes claimed the Arkaig lands as part of Eva's inheritance. The Camerons, occupying the ground, claimed it as their own. They fought at Drumlui in either 1330 or 1337, depending on which chronicle you trust. They went on fighting, on and off, for the next three centuries. Multiple kings tried to settle the matter. The Court of Session in Edinburgh took it up repeatedly. None of the rulings stuck. By the 1660s, both clans had committed substantial resources to the Royalist cause during the civil wars, which gave the Camerons useful political leverage.

In June 1661, Lord Glencairn wrote from London urging the Edinburgh courts to freeze any Mackintosh action against the Camerons, hinting that Charles II had a plan to reward Cameron loyalty. No royal plan ever materialised. So in July 1662, Mackintosh obtained a Decree of Removal against the Camerons. The next year he pushed further and had the entire Clan Cameron declared outlaws under a Commission of Fire and Sword. The noblemen authorised to enforce it all told Mackintosh to take the cash settlement Cameron had been offering, about 3,600 pounds in English money, and stop wasting everyone's time. The Duke of Rothes, Lord Chancellor of Scotland, suspended the Commission in January 1665 pending a Privy Council review. Mackintosh, arrested in Edinburgh and bound to keep the peace, simply went home and called out the clan.

Mackintosh led 1,500 men south from his territory to the foot of Loch Lochy. Cameron, knowing they were coming, assembled his own force, joined by MacGregors who owed him favours from the 1650s Royalist rising, and by MacIans of Glencoe. The Camerons withdrew across the Arkaig river to Achnacarry, securing the only crossable ford. For seven days the two armies faced each other across the water. Then a Campbell of Glenorchy, the future Earl of Breadalbane, arrived with orders from Edinburgh to end the dispute by negotiation or by force. While he opened talks with Mackintosh, Cameron sent the bulk of his men on an eighteen-mile flanking march around the western end of Loch Arkaig and back along the north shore, aiming to surprise the Mackintosh army from behind. Before that movement was completed, the Mackintoshes accepted terms.

The contract was signed at the House of Clunes. The Camerons bought Loch Arkaig and Glen Loy outright. To raise the money, Cameron took a loan from the Earl of Atholl, who hoped to weaken the Campbells in the region, but Argyll counter-offered a lower rate with strings: the Camerons had to pay 100 pounds Scots in feu duty annually and acknowledge Argyll as feudal superior of the lands they were buying. Cameron took the deal. His descendants were still paying rent to Argyll's factor in 1749. The Camerons themselves called it a Pyrrhic victory, because pursuing the claim across the centuries had cost them lands worth four times what they paid to settle it. Achnacarry Castle, where they had met the Mackintosh army, still stands in Cameron hands today, though the war that came eighty years later, the 1745 rising, would damage it heavily.