Gibbon’s confidence [General Observations on the Fall of the Roman Empire in the West in Vol VI] in the inviolability of an American asylum for the Western Civilization would have been justified if – but only if – the aggressor’s part had been played in reality by those arrested Nomad riders [Nomadism is one of Toynbee’s “arrested civilizations”] who had been cast for it in Gibbon’s imagination. If the Continental Power that was under suspicion in A.D. 1952 of entertaining designs of world-wide conquest had been, once again, the Mongols, the peoples of the Western World would assuredly have had better reason this time for counting on the survival of their own distinctive culture than they had had in A.D. 1238, when they had been facing the prospect of a Mongol occupation of the West European peninsula of Asia without having any reassuring Transatlantic asylum at their backs. In A.D. 1952 they could have taken comfort in reminding themselves that in A.D. 1281 the forces of a Mongol Empire, which at that date had been mistress of the Continent from the shores of the Pacific Ocean to the shores of the Persian Gulf and the Baltic Sea, had been thrown back ignominiously from the beaches of Japan; for a cavalry Power which had proved impotent to conquer a cluster of small islands separated from the Continent by only a hundred miles of sea at the nearest point would have had no prospect, if she had occupied the European coastline of the Continent that the Germans held in June 1940, of being able to conquer the great island of North America on the farther side of a nearly two thousand-miles-broad Atlantic Ocean, or even the sister island of South America, which was divided by not less than sixteen hundred miles of sea from the Continent at the Straits of Dakar, where the westward bulge of Africa approached closest to the eastward bulge of Brazil. Indeed, the fiasco of Qubilay Khan’s attempt on Japan suggests that even the twenty-miles-wide Straits of Dover, which had foiled Napoleon and foiled Hitler when the local Continental war-lord of the day had had the whole of Europe under his command, might have proved impassable for Qubilay Khan in spite of his commanding the Asiatic mass as well as the European extremity of the Continent. But the historic immunity of the isles from conquest by Continental war-lords had been due to the comparative innocuousness of even a sedentary community’s most formidable weapons of offence until a hundred years and more after the date at which Gibbon had been writing; and no one who had lived through the war of A.D. 1939-45 could be blind to the truth that, since then, times had changed. The weapons with which Hitler had come within an ace of conquering Britain, and with which the combined forces of the United States and the British Commonwealth had succeeded thereafter in conquering Hitler’s vaunted Festung Europa, were indications that in a future world war the conquest of North America might not be beyond the reach of a Power controlling the aggregate resources of the Old World and capable of forging this incomparably vast store of war potential into unprecedentedly potent weapons through a mastery of an ever improving Western technology.
A Study of History, Vol IX, OUP, 1954