Few measures have won a greater popularity than the Triple Alliance. "It is the only good public thing," says Pepys, "that hath been done since the King came to England." Even Dryden, writing at the time as a Tory, counted among the worst of Shaftesbury's crimes that " the Triple Bond he broke." In form indeed the Alliance simply bound Lewis to adhere to terms of peace proposed by himself, and those advantageous terms. But in fact it utterly ruined his plans. It brought about too that union of the powers of Europe against which, as Lewis felt instinctively, his ambition would dash itself in vain. It was Arlington's aim to make the Alliance the nucleus of a greater confederation; and he tried not only to perpetuate it, but to include within it the Swiss Cantons, the Empire, and the House of Austria. His efforts were foiled; but the "Triple Bond" bore within it the germs of the Grand Alliance which at last saved Europe. To England it at once brought back the reputation which she had lost since the death of Cromwell. It was a sign of her re-entry on the general stage of European politics, and of the formal adoption of the balance of power as a policy essential to the welfare of Europe at large.
But it was not so much the action of England which had galled the pride of Lewis, as the action of Holland. That "a nation of shopkeepers" (for Lewis applied the phrase to Holland long before Napoleon applied it to England) should have foiled his plans at the very moment of their realization, "stung him," he owned, "to the quick." If he refrained from an instant attack it was to nurse a surer revenge. His steady aim during the four years which followed the Peace of Aix-la-Chapelle was to isolate the United Provinces, to bring about the neutrality of the Empire in any attack on them, to break the Triple Alliance by detaching Sweden from it and securing Charles, and to leave the Dutch without help, save from the idle goodwill of Brandenburg and Spain. His diplomacy was everywhere successful, but it was nowhere so successful as with England. Charles had been stirred to a momentary pride by the success of the Triple Alliance, but he had never seriously abandoned his policy, and he was resolute at last to play an active part in realizing it. It was clear that little was to be hoped for from his old plans of winning toleration for the Catholics from his new ministers, and that in fact they were resolute to bring about such a union of Protestants as would have been fatal to his designs.
From this moment he resolved to seek for his advantage from France. The Triple Alliance was hardly concluded when he declared to Lewis his purpose of entering into an alliance with him, offensive and defensive. He owned to being the only man in his kingdom who desired such a league, but he was determined to realize his desire, whatever might be the sentiments of his ministers. His ministers, indeed, he meant either to bring over to his schemes or to outwit. Two of them, Arlington and Sir Thomas Clifford, were Catholics in heart like the King; and they were summoned, with the Duke of York, who had already secretly embraced Catholicism, and two Catholic nobles, to a conference in which Charles, after pledging them to secrecy, declared himself a Catholic, and asked their counsel as to the means of establishing the Catholic religion in his realm. It was resolved to apply to Lewis for aid in this purpose; and Charles proceeded to seek from the King a "protection," to use the words of the French ambassador, "of which he always hoped to feel the powerful effects in the execution of his design of changing the present state of religion in England for a better, and of establishing his authority so as to be able to retain his subjects in the obedience they owe him." The fall of Holland was as needful for the success of the plans of Charles as of Lewis; and with the ink of the Triple Alliance hardly dry, Charles promised help in Lewis's schemes for the ruin of Holland and the annexation of Flanders. He offered therefore to declare his religion and to join France in an attack on Holland, if Lewis would grant him a subsidy equal to a million a year.
In the event of the King of Spain's death without a son Charles pledged himself to support France in her claims upon Flanders, while Lewis promised to assent to the designs of England on the Spanish dominions in America. On this basis, after a year's negotiations, a secret treaty was concluded at Dover in an interview between Charles and his sister Henrietta, the Duchess of Orleans. It provided that Charles should announce his conversion, and that in case of any disturbance arising from such a step he should be supported by a French army and a French subsidy. War was to be declared by both powers against Holland, England furnishing a small land force, but bearing the chief burthen of the contest at sea, on condition of an annual subsidy of three hundred thousand pounds.
Nothing marks better the political profligacy of the age than that Arlington, the author of the Triple Alliance, should have been chosen as the confidant of Charles in his treaty of Dover. But to all save Arlington and Clifford the King's change of religion or his political aims remained utterly unknown. It would have been impossible to obtain the consent of the party in the royal council which represented the old Presbyterians, of Ashley or Lauderdale or the Duke of Buckingham, to the Treaty of Dover. But it was possible to trick them into approval of a war with Holland by playing on their desire for a toleration of the Nonconformists. The announcement of the King's Catholicism was therefore deferred; and a series of mock negotiations, carried on through Buckingham, ended in the conclusion of a sham treaty which was communicated to Lauderdale and to Ashley, a treaty which suppressed all mention of the religious changes or of the promise of French aid in bringing them about, and simply stipulated for a joint war against the Dutch. In such a war there was no formal breach of the Triple Alliance, for the Triple Alliance only guarded against an attack on the dominions of Spain, and Ashley and his colleagues were lured into assent to it in 1671 by the promise of a toleration on their own terms.