In that spring of 1947, America bestrode the planet as never before or since. Alone on earth the US possessed nuclear weapons. It accounted for 50 per cent of global output. Europe, by contrast, was ravaged and penniless, swathes of it on the brink of starvation. To the east lay a menacing Soviet Union, waiting for the Old Continent to fall into communism's lap.
Something had to be done. But only America could do it. For the Truman Administration, the problem was less Stalin than isolationists at home, hostile then as now to entanglement in a Europe which twice in 30 years had dragged the US into wars not of its making. Marshall's pitch, however, was masterly, a uniquely American blend of idealism, anti-communism and self advantage.
In the quadrangle of Harvard Yard that June day, he warned of possible terminal breakdown in Europe. Its needs were "so much greater than her present ability to pay that she must have substantial additional help or face economic, social and political deterioration of a very grave character." Not only would that cause "disturbances" abroad: "The consequences to the economy of the United States should be apparent to all."
The impact across the Atlantic was enormous. Cleverly, the State Department had finessed the domestic opposition, breathing not a word about the speech to anti-interventionist newspapers like the Chicago Tribune but making sure the British knew well in advance of the huge story on the way.
And huge it was, whatever the assertions of revisionist historians that the money disbursed meant little to the US and that Europe would have recovered quickly, with or without largess from Washington.
The Russians and their satellites would stay out. But 16 countries, including today's European Union in its virtual entirety, would participate. Over four years, $13bn of American help was provided. Britain would receive $3.2bn, France $2.7bn, Italy $1.5bn, and the future West Germany $1.4bn. The transfer represented around 2 per cent of America's GDP. An equivalent programme today would be worth some $500bn (pounds 300bn).
The consequences of Marshall's speech are all around us. It was the economic prefiguration of Nato, now poised to embrace, if not Russia itself, at least Poland and Czechoslovakia. Even institutionally, the Plan lives on. The Organisation for Economic Cooperation and Development is daughter of the Organisation for European Economic Co-operation (OEEC), created in 1948 to put Marshall's vision into effect.