IT was on this date in 1603 that one of the bloodiest and certainly one of the most one-sided of all clan battles was fought between Clan MacGregor and Clan Colquhoun in Glen Fruin, which lies between Loch Lomond and the Gare Loch.

Nowadays the Glen contains the A817 which is the upper route to the nuclear submarine base at Faslane. And for convenience sake I will refer to the clan as MacGregor, though I know there were and are different spellings.

The background to the battle was complex, involving the machinations of the Seventh Earl of Argyll, Archibald Campbell, who had been made responsible for keeping Clan MacGregor in His Majesty’s peace after their previous raids on neighbouring clans and territories. He failed to do so, and instead encouraged the MacGregors to raid the cattle and territory of his enemy, Alexander Colquhoun, chief of that clan. The Colquhouns were based around Luss on the west side of Loch Lomond, with the clan seat at Rossdhu and had been feuding with the MacGregors for decades, if not centuries.

Sir Walter Scott in Rob Roy describes how “two of the Macgregors being benighted, asked shelter in a house belonging to a dependent of the Colquhouns, and were refused. They then retired to an outhouse, took a wedder from the fold, killed it, and supped off the carcase, for which they offered payment to the owner. The Laird of Luss, however, unwilling to be propitiated by the offer made to his tenant, seized the offenders, and by the summary process which feudal barons had at their command, caused them to be condemned and executed.”

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It is William Fraser, official historian of the Colquhouns, who tells the story of the raid on Glenfinlas by MacGregors in late 1602. They carried off sheep and cattle and slew several tenants of Alexander Colquhoun who promptly took the newly-widowed women to Stirling to show King James VI their men’s “bluidie sarks”.

James responded by giving Colquhoun letters of fire and sword to tackle the MacGregors – in effect death warrants for the entire clan. There is some dispute about whether clan chiefs Allaster MacGregor and Alexander Colquhoun met to discuss their grievances, but there is little doubt as to what happened next – with fewer than 300 men, the MacGregors took on a force more than twice that number, and what started out as a battle ended up as a massacre.

Fraser wrote an account of the battle more than 250 years later, but his writing was based on the Colquhoun family’s own collections of letters and reports and is therefore more likely to be accurate about the facts – you can check for yourself as his Colquhoun history is in the National Library of Scotland.

Fraser describes how the MacGregors split into two divisions, one under Allaster and the other led by his brother John who took up positions for their ambush, as Fraser describes: “One of them at the head of the glen, and the other in ambuscade near the farm of Strone, at a hollow or ravine called the Crate.

“The Colquhouns came into Glenfruin from the Luss side, which is opposite Strone – probably by Glen Luss and Glen Mackurn. Alexander Colquhoun pushed on his forces in order to get through the glen before encountering the MacGregors; but, aware of his approach, Allaster MacGregor also pushed forward one division of his forces and entered at the head of the glen in time to prevent his enemy from emerging from the upper end of the glen, whilst his brother, John MacGregor, with the division of his clan, which lay in ambuscade, by a detour, took the rear of the Colquhouns, which prevented their retreat down the glen without fighting their way through that section of the MacGregors who had got in their rear.”

In short, Allaster MacGregor led a classic Highland charge against the Colquhouns who were bogged down in a marshy morass that rendered horses useless and made it impossible for the poorly-trained infantry to maintain order. The Colquhoun side broke and ran – straight into the other division of MacGregors.

Fraser continues: “The Colquhouns soon became unable to maintain their ground, and, falling into a moss at the farm of Auchingaich, they were thrown into disorder, and made a hasty and disorderly retreat, which proved even more disastrous than the conflict, for they had to force their way through the men led by John Macregor, whilst they were pressed behind by Allaster, who, reuniting the two divisions of his army, continued the pursuit.”

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Fraser concludes: “The success of the stratagem by which the Colquhouns were thus placed between two fires seems to be the only way of accounting for the terrible slaughter of the Colquhouns and the much less loss of the MacGregors.”

About 120 to 140 Colquhouns died. Just a handful of MacGregors perished, but the authorities clamped down hard on them.

One chronicler wrote: “All who had been at the conflict of Glenfruin, and at the spoliation and burning of the lands of the Laird of Luss, were prohibited, under the penalty of death, from carrying any weapon except a pointless knife to eat their meat.”

In total, 35 of the clan Gregor were executed after trial between May 1603 and March 1604. Among these was Allaster Macgregor, who surrendered himself to the Earl of Argyll and was brought to trial in Edinburgh on January 20, 1604. Argyll did nothing to save his erstwhile ally, and after a perversion of a trial – the jury was hopelessly biased – Allaster and 11 of his clansmen were executed.

King James proscribed the very name of MacGregor, a ban which was not lifted until 1784.