The Earl of Annandale's and Lord Belhaven's troops of horse, having been completed and equipped, took the field, and formed part of the force under Major-General Mackay, which engaged the Highlanders and Irish, under Viscount Dundee, at the pass of _Killicrankie_, on the 27th of July, 1689, and were the only cavalry corps with the army on that occasion[1]. For a short time after the commencement of the action, the advantage was on the side of Major-General Mackay. When the infantry began to give way before the superior numbers of the clans, the two troops of horse were ordered forward,--one on the right, and the other on the left,--to attack the flanks of the opposing army; but, being untrained men, instead of dashing, sword in hand, upon the adverse ranks, they halted at a short distance, and commenced a straggling fire with carbines and pistols. This mode of attacking a body of men on foot of very superior numbers, could not fail to prove disastrous; and the two troops were speedily driven from the field with loss. The army was defeated; but the ability evinced by Major-General Mackay, in conducting the retreat, and in assembling another army, with the loss of the Jacobite commander, Viscount Dundee, who was killed at the commencement of the action, occasioned the result to be less disastrous than was anticipated, and the Highlanders were forced to take refuge in their mountain fastnesses. [Sidenote: 1690] In the beginning of 1690 the newly-raised horse were formed into a regiment, of only three troops, of which the Earl of Eglintoun was appointed colonel,--the Honorable William Forbes (eldest son of Lord Forbes), lieut.-colonel,--and Sir George Gordon, of Edinglassie, major; the dragoons were also formed into a regiment of three troops, under the command of Lord Cardross,--Jackson, lieut.-colonel, and--Guthrie, major; at the same time three of the newly-raised regiments of foot were incorporated into one, which were placed under the orders of Colonel Cunningham. During the subsequent contest the two cavalry corps performed much harassing and faithful service; they took part in several skirmishes, and evinced intrepidity and valour; the clans were repulsed and driven back to the mountains; garrisons were placed in the heart of the Highland districts, and the adherents of King James lost all hope of success.