George Canning, the English statesman to whom belonged much of the credit for the Constitution of Cadiz, thought out a way to punish the Spanish king for his perfidy. King Ferdinand was planning, with the Island of Cuba as a base, to begin a campaign that should return his rebellious American colonies to their allegiance, for they had taken advantage of disturbances in the Peninsula to declare their independence. England proposed to the United States that they, the two Anglo-Saxon nations whose ideas of liberty had unsettled Europe and whom the alliance would have attacked had it dared, should unite in a protectorate over the New World. England was to guard the sea and the United States were to furnish the soldiers for any land fighting which might come on their side of the Atlantic.
World politics had led the enemies of England to help her revolting colonies, Napoleon's jealousy of Britain had endowed the new nation with the vast Louisiana Territory, and European complications saved the United States from the natural consequences of their disastrous war of 1812, which taught them that union was as necessary to preserve their independence as it had been to win it. Canning's project in principle appealed to the North Americans, but the study of it soon showed that Great Britain was selfish in her suggestion. After a generation of fighting, England found herself drained of soldiers and therefore she diplomatically invited the coöperation of her former colonies; but, regardless of any formal arrangement, her navy could be relied on to prevent those who had played her false from transporting large armies across the ocean into the neighborhood of her otherwise defenseless colonies. That was self-preservation.
President Monroe's advisers were willing that their country should run some risk on its own account, but they had the traditional American aversion to entangling alliances. So the Cabinet counseled that the young nation alone should make itself the protector of the South American republics, and drafted the declaration warning the world that aggression against any of the New World democracies would be resented as unfriendliness to the United States.
It was the firm attitude of President Monroe that compelled Spain to forego the attempt to reconquer her former colonies, and therefore Mexico and Central and South America owe their existence as republics quite as much to the elder commonwealth as does Cuba.