Lovat became involved, with tragic consequences, in the succession dispute within Clanranald triggered by the death of the 7th chief, Alexander Macdonald, in c.1530.
However, Cameron's meddling in the affair was resented by the most powerful peer in northern Scotland, George Gordon, 4th Earl of Huntly, a nephew of James V. In 1540, John was arrested and imprisoned by the king, and his uncle, Ranald Gallda, promptly asserted his own claim to the chiefship of Clanranald with Lovat's backing, declaring John's birth to be illegitimate.
After John's release from prison and return to Lochaber, Ranald was unable to cling to power and fled to Lovat, who gave him refuge.
Returning east from this raid by a different route from Huntly, Lovat was pursued by a force of Macdonalds and Camerons, who overtook the Frasers at the head of Loch Lochy on 15 July 1544.
Although Ranald Gallda too was slain in the battle of Loch Lochy, leaving John Moidartach secure in the chiefship, an enraged Huntly swiftly returned to Lochaber in force and arrested Cameron, who was put to death at Elgin in 1547.