His Jacobite partialities were now placed in opposition to his sense of the obligations which he owed to the indirect protection of the Duke of Argyle.

But the desire of "drowning his sounding steps amid the din of general war" induced him to join the forces of the Earl of Mar, although his patron the Duke of Argyle was at the head of the army opposed to the Highland insurgents.
The MacGregors, a large sept of them at least, that of Ciar Mhor, on this occasion were not commanded by Rob Roy, but by his nephew already mentioned, Gregor MacGregor, otherwise called James Grahame of Glengyle, and still better remembered by the Gaelic epithet of _Ghlune Dhu, i.e._ Black Knee, from a black spot on one of his knees, which his Highland garb rendered visible.

There can be no question, however, that being then very young, Glengyle must have acted on most occasions by the advice and direction of so experienced a leader as his uncle.
The MacGregors assembled in numbers at that period, and began even to threaten the Lowlands towards the lower extremity of Loch Lomond.

They suddenly seized all the boats which were upon the lake, and, probably with a view to some enterprise of their own, drew them overland to Inversnaid, in order to intercept the progress of a large body of west-country whigs who were in arms for the government, and moving in that direction.
The whigs made an excursion for the recovery of the boats.

Their forces consisted of volunteers from Paisley, Kilpatrick, and elsewhere, who, with the assistance of a body of seamen, were towed up the river Leven in long-boats belonging to the ships of war then lying in the Clyde.