Castlereagh, Lord Londonderry, would naturally have been the man chosen by England for such a purpose; but Londonderry was gone, and it was resolved to send no less a person than the Duke of Wellington in his place. The Duke was naturally the man most welcome to the Continental Sovereigns whom England could possibly send to take part in such a meeting. But for his military genius a Bourbon king would not have been on the throne of France, and the arrangements of the Congress of Vienna could never have been undertaken. The Duke of Wellington had no particular foreign policy of his own, although it must be remembered that he had wisely refrained from pledging his Government to the principles of the Holy Alliance. The Continental Sovereigns, however, believed that in the mere nomination of the Duke of Wellington they had the best guarantee of England's sympathy, approval, and support. The object for which the Congress was ostentatiously summoned was not, however, in the first instance to deal with anything but the condition of Greece, and to prevent, if possible, a war between Russia and Turkey. The Duke of Wellington, meanwhile, was informed by a French statesman that the condition of Spain would also be brought under the notice of the Congress: and the Duke of Wellington, who had just arrived in Paris, wrote home to Canning for instructions as to the course he was to pursue. Canning had been only a few days in office; but he soon made up his mind. He had never had much doubt that the Congress would seek to deal with subjects which came nearer to the hearts of most of the Sovereigns than the condition of struggling Greece.

Canning sent a reply to the Duke of Wellington, the important part of which deserves quotation as a document of the greatest moment, a proclamation of the new era which Canning was introducing into the foreign policy of England. "If," wrote Canning, "there be a determined project to interfere by force or by menace in the present struggle in Spain, so convinced are his Majesty's Government of the uselessness and danger of any such interference, so objectionable does it appear to them in principle, as well as impracticable in execution, that when the necessity arises, or, I would rather say, when the opportunity offers, I am to instruct your Grace at once frankly and peremptorily to declare that to any such interference, come what may, his Majesty will not be a party." The result of these instructions was decisive. France, through her representative, strongly argued for an interference with the Spanish Revolution by force of arms, and insisted that the condition of France herself was unsafe while only the Pyrenees divided her from the forward movement in Spain. But France might plead as she would. The instructions given by Canning to the Duke of Wellington made England's purpose too plain to be mistaken; and the baffled Sovereigns did not venture to pass any resolution in favour of any interference in Spanish affairs. Canning never had the slightest belief in the policy of governing Europe by means of Congresses. There were then two great principles in direct opposition - the principle of those who believed that a set of European kings had only to get together, and agree, in order to make their decrees a command to the civilised world; and the principle of those who believed with Canning, that the affairs of each country can only in the end be settled by its inhabitants. Here, then, was the actual parting of the ways. Canning had laid down a policy which was absolutely new at the time but which became, with some slight and fitful deviations, the settled foreign policy of England.

Canning himself would undoubtedly have preferred, on the whole, to send no English representative to the Congress of Verona; but he thought so sharp a decision might be unwise at such a moment; and he believed that he could better attain his own ends by the course which he actually adopted. His own great objects were two in number. The first was to keep his own country, and if possible all other countries, at peace; and his minor and more immediate object was the practical dissolution of the Holy Alliance. It is not too much to say that George Canning was the first Minister for England's foreign affairs who ever set up that policy of peace. His apprehensions as to the purpose of the Congress of Verona were only too soon justified. It was made known that the French army was to be sent into Spain to assist the Spanish Bourbon king in abolishing the Constitution and crushing all Spaniards who opposed his measures. The Duke of Wellington followed the instructions of his chief, as, to render him only justice, he always did : he offered his strong remonstrance; he made known the determination of England as set forth by Canning; and he withdrew from the Congress. Canning clearly saw what the course of action threatened with regard to Spain meant as regarded other countries. It was a menace to Portugal, which might be expected to join with Spain in repelling the French invasion; and it was a menace also to Spain's South American Colonies. On the 14th of April, 1823, Canning proclaimed his policy to the House of Commons. He insisted that if Portugal at her own choice and at her own risk assisted Spain in repelling the French, there was no occasion for England's intervention; but he declared that if Portugal should remain quiescent, and should nevertheless be attacked by France, that attack would bring Great Britain into the field with all her force to support the independence of her ancient and faithful ally. So far as the South American Colonies were concerned, Canning made known the policy of England in the frankest and most explicit language. "It was clear," he said, "that Spain, though claiming them as hers by right, had, in fact, lost all power and influence over them. If the expected war were to break out, and France should, as one of the events of that war, invade and take possession of any of them, so that it might become a question whether the Colonies should be ceded, and to whom; then it was of importance for the world to know that the British Government considered the separation of the South American Colonies from Spain to have been effected so completely that England would not admit for an instant any claim on the part of Spain to hand over to another Power any of those Colonies which had ceased to be under her direct and positive influence." In other words, the British Government regarded the South American Colonies as no longer belonging to Spain; but England did not feel charged with securing their independence. If, however, Spain were to proceed to the cession of any of those Colonies to some foreign Power, England would feel bound to interfere; and to such a declaration Canning added, "the British Government had at last been forced." Canning carried his policy by a triumphant majority - an overwhelming majority - in the House of Commons.