Having gone thus far with the men whose cause he had adopted, and even exceeded them in some of his proceedings, the Earl of Lauderdale was now to undergo that change to which extreme zeal is so often subject. The recoil was manifested in 1647, when he was sent, with other Scottish commissioners, to persuade the king to sign the Covenant. This was at Hampton Court, while his majesty enjoyed a temporary liberty; but after Charles was confined as a prisoner in Carisbrook Castle, Lauderdale and the commissioners so effectually wrought, that they prevailed with him to sign the Engagement, a secret proposal, which, formed a separate treaty for Scotland. By the terms of this compact the king agreed, among other important concessions, that the Scots should be equally admitted into all foreign employments with the Englisli; that a third part of all the offices about the king, queen, and prince, should be bestowed upon Scotchmen, and that the king and prince, or one of them, should frequently reside in Scotland. But the crowning concession of all was contained in his consent that the church throughout his dominions should be subjected to the provisions of what he had already termed their "damnable covenant." It requires no profound knowledge of that kind of kingcraft which Charles inherited from his father, to surmise with what facility he would have broken these engagements, had he been restored to place and power. His reposition they engaged on their part to do their utmost to effect, by raising an army for the invasion of England. The Earl of Lauderdale, thus pledged to become a staunch royalist, and with the restoration of royalty in full perspective, of which he might hope to reap the first-fruits, returned to Scotland, and set everything in train for the accomplishment of his promises. In conformity with the terms of the Engagement, he also went to Holland, for the purpose of persuading the Prince of Wales to put himself at the head of the Scottish army destined for the invasion of England; but in this delicate negotiation he conducted himself with such dictatorial arrogance of temper, and in such a coarse blustering manner, that the prince saw little temptation to follow such a leader, especially into the dangers of a doubtful war, and therefore contented himself with his residence at the Hague. Here; too, Lauderdale was compelled to remain, just when he was on the point of embarking for Scotland, for at that critical moment tidings arrived of the utter defeat of the Scottish army by Cromwell at Preston, the condemnation of the Engagement by the Scottish Parliament, and the pains and penalties denounced against its authors and subscribers. He returned to the little court at the Hague, which he appears only to have disturbed by his divisive counsels and personal resentments. Such was especially his conduct in the plan of the last fatal campaign of the Marquis of Montrose, whom he seems to have hated with a perfect hatred. On Charles II. being invited to Scotland, to be invested with the ancient crown of his ancestors, Lauderdale accompanied him, but was so obnoxious to the more strict Presbyterians for his share in the Engagement, that he was forbid to enter the royal presence, and even compelled to fly into concealment until the popular anger had abated. On being recalled to the royal councils, he seems to have ingratiated himself wonderfully with the young king, who perhaps found in him a less severe censor than Argyle, and the other leaders of the Covenant by whom he was surrounded. This favour, however, for the present was of little advantage to him, as it made him a necessary participator in the ill-fated expedition into England, where he was taken prisoner at the battle of Worcester. For nine long years after he was subjected to close confinement in the Tower of London, Portland Castle, and other places, until the arrival of Monk in London, in 1660, by whom he was set at liberty.

On recovering his freedom, and seeing how the wind was setting in favour of royalty, Lauderdale repaired to the Hague, and was received by Charles II. with greater favour than before. To this, indeed, his nine years of bondage must have not a little contributed. Perhaps the king also saw in Lauderdale the fittest person through whom he might govern Scotland with absolute authority, and revenge himself upon the Presbyterians, by whom he had been so strictly curbed and schooled. Shortly after the Restoration, therefore, he was appointed secretary of state for Scotland, and soon after, the influential offices were added of president of the council, first commissioner of the treasury, extraordinary lord of session, lord of the bedchamber, and governor of Edinburgh Castle. In the meantime, however, he did not rule alone; for while his place was the court at London, from which his influence could only be indirect upon Scotland, the Earls of Middleton and Rothes, bitter enemies of Presbyterianism, and unscrupulous actors in the restoration of Episcopacy, had the chief direction of Scottish affairs, which they signalized by a frightful course of persecution. But on Middleton being disgraced in 1662, and Rothes in 1667, Lauderdale, who had procured their removal, was now enabled to rule the north without rival or impediment.

This change in the government of Scotland had at first a propitious appearance. Lauderdale had all along been the advocate of a limited monarchy, as well as a staunch adherent of Presbyterianism; and it was hoped, by a people who had been trampled into the dust by the rule of Middleton, Rothes, and Archbishop Sharp, that his sympathies would have been awakened in their behalf. Nor were these expectations in the first instance disappointed. He procured the demolition of those fortresses which Cromwell had erected to overawe the country. He prevented the establishment of a Scottish Privy Council that was to sit in London, by which the liberties of Scotland would have been imperilled. He also obtained the royal pardon for those of his countrymen who had been arrayed against Charles I. during the Civil war. But more than all, he steadily resisted the imposition of Episcopal rule upon the country, disbanded the standing army, by whom the people had been persecuted and plundered, and dismissed the principal agents under whom this misrule had been conducted. But events subsequently showed that he cared neither for religion nor liberty, neither for Presbyterianism nor constitutional government, but was all for royal supremacy, and his own personal interests as connected with it; and that for these he was prepared to sacrifice everything, or worship anything, whether in church or state. He thus became the most merciless persecutor of the Covenanters, whom he sent "to glorify God at the Grass-market;" and the most despotic of tyrants, when, upon a remonstrance of the noblest and highest of the kingdom, he made bare his arms above the elbows at the council board, and "swore by Jehovah that he would make them enter into these bonds." In the meantime, the king took care that so compliant an instrument for the entire subjugation of Scotland to the royal will, should have ample means and authority for the purpose, for in May, 1672, he created him Marquis of March and Duke of Lauderdale; a month afterwards, Knight of the Garter; and in June, 1674, he elevated him into the English peerage, by the titles of Viscount Petersham and Earl of Guilford, and appointed him a seat in the English Privy Council.

It was these last honours, which raised Lauderdale to the culminating point, that occasioned his downfall. Having now a place in the English government, he endeavoured to bring into it the same domineering arrogance which had disgusted the people of Scotland, and was a member of that junto of five ministers called the "Cabal," from the initials of their names, by which the whole empire for a time was governed. But he soon became odious to his colleagues, who were weary of his arrogance; to the people, who regarded him as an upstart and an alien; and to the Duke of York, who thought he had not gone far enough in severity, and suspected him of being a trimming Presbyterian and secret enemy to the divine right of kings. Thus mistrusted and forsaken by all parties, he was deprived of all his offices and pensions in the beginning of 1682, and thrown aside as a worn-out political tool, that could be serviceable no longer. These bitter reverses, combined with old age and gross unwieldiness of body, hastened his death, which occurred at Tunbridge, in the summer of the same year. It was recorded by Burnet, and eagerly noticed by the Covenanters of Scotland, whom he had so cruelly betrayed and persecuted, that when he died, "his heart seemed quite spent; there was not left above the bigness of a walnut of firm substance; the rest was spungy; liker the lungs than the heart."

Such is but a brief sketch of the political life of one with whose proceedings so large a portion of Scottish biography is more or less connected. The character of the Duke of Lauderdale is thus severely but truthfully limned by Bishop Burnet, who knew him well, but was no admirer of his proceedings:—"He was very learned, not only in Latin, in which he was a master, but in Greek and Hebrew. He had read a great deal of divinity, and almost all the historians, ancient and modern, so that he had great materials. He was a man, as the Duke of Buckingham once called him to me, of a blundering understanding. He was haughty beyond expression; abject to those he saw he must stoop to, but imperious to all others. He had a violence of passion that carried him often to fits like madness, in which he had no temper. If he took a thing wrong, it was a vain thing to study to convince him; that would rather provoke him to swear he would never be of another mind. He at first despised wealth; but he delivered himself up afterwards to luxury and sensuality, and by that means he ran into a vast expense, and stuck at nothing that was necessary to support it. . . . .He was in his principles much against Popery and arbitrary government; and yet, by a fatal train of passions and interests, he made way for the former, and had almost established the latter; and whereas some, by a smooth deportment, made the first beginnings of tyranny less discernible and unacceptable, he, by the fury of his behaviour, heightened the severity of his ministry, which was liker the cruelty of an inquisition, than the legality of justice. With all this he was a Presbyterian, and continued his aversion to King Charles I. and his party to his death." So unfavourable a disposition and character was matched by his personal appearance. "He was very big," says the same authority; "his hair red, hanging oddly about him. His tongue was too big for his mouth, which made him bedew all that he talked to; and his whole manner was rough and boisterous, and very unfit for a court."