On the 1st of March, 1681, Kenneth was served heir male to his great-grandfather, Lord Mackenzie of Kintail, in his lands in the Lordship of Ardmeanach and in the Earldom of Ross; was made a member of the Privy Council by James II. on his accession to the throne in 1685, and chosen a Knight Companion of the Thistle, on the revival of that ancient Order in 1687. The year after the Revolution Seaforth accompanied his Royal master to France, but when that Prince returned to Ireland in the following year to make a final effort for the recovery of his kingdom, he was accompanied thither by the Earl. There he took part in the siege of Londonderry and in other engagements, and as an expression of gratitude James created him Marquis of Seaforth, under which title he repeatedly appears in various legal documents. This well-meant and deserved honour, however, came too late in the falling fortunes and declining powers of the ex-King, and does little more than mark his Royal confirmation of the steady adherence of the chiefs of Kintail to the cause of the unfortunate Stuarts. Viscount Dundee in a letter to the "Laird of Macleod," dated "Moy, June 23, 1689" [About this time Viscount Tarbat boasted to General Mackay of his great influence with his countrymen, especially the Clan Mackenzie, and assured him "that though Seaforth should come to his own country and among his friends, he (Tarbat) would overturn in eight days more than the Earl could advance in six weeks yet be proved as backward as Seaforth or any other of the Clan. And though Redcastle, Coul, and others of the name of Mackenzie came, they fell not on final methods, but protested a great deal of affection for the cause." - "Mackay's Memoirs."] in which he details his own and the King's prospects, gives a list of those who are to join him. "My Lord Seaforth," he says, "will be in a few days from Ireland to raise his men for the King's service;" but the fatal shot which closed the career of that brilliant star and champion of the Stuart dynasty at Killiecrankie, arrested the progress of the family of Seaforth in the fair course to all the honours which a grateful dynasty could bestow; nor was the family of Kintail singular in this respect - seeing its flattering prospects withered at, perhaps, a fortunate moment for the prosperity of the Empire. Jealousies have now passed away on that subject, and it is not our business to discuss or in any way confound the principles of contending loyalties. To check the proceedings of the Mackenzies, Mackay placed a garrison of a hundred Mackays in Brahan Castle, the principal seat of the Earl, and an equal number of Rosses in Castle Leod, the mansion of Viscount Tarbat, both places of strength, and advantageously situated for watching the movements of the Jacobite Mackenzies. ["Life of General Mackay," by John Mackay of Rockfield, pp. 36-37.]