They were sons of the Great Depression, from an America still largely rural, of dust bowl and ruined farms, and of factories silenced during the 1930s that did not come to life again until war spending began. They were from a racially segregated society (and army) and a country that only attack at Pearl Harbor had wrenched from its historical isolation.
President George Bush is arguing that the invasion of Iraq is no more than another manifestation of an American crusade for liberty that began at Chateau-Thierry and Belleau Wood in June 1918, swept forward to Normandy 1944, and now has reached Baghdad.The truth is otherwise.
The First World War produced a desire never again to mix in Europe's 'power politics'. Only Japan's attack on Pearl Harbor - and Germany's subsequent declaration of war on America - made the US do so. Winston Churchill convinced Franklin Roosevelt (against popular desire for revenge on Japan) that Hitler should be dealt with first.
The only American help to the democracies had been agreement in 1939 to 'cash and carry' arms sales. Despite Churchill's arguments, and a desperate plea from France in 1940, there was nothing more until 'lend-lease' grants and loans in March 1941. In August that year, Churchill and Roosevelt signed the Atlantic Charter. It condemned 'territorial changes that do not accord with the freely expressed wishes of the peoples concerned'.
This was moral help, and an implied promise: an unprecedented statement by a neutral country in support of a belligerent. But if there had been no Pearl Harbor, there might have been no sequel. In September 1939, the US army, including what then was the Army Air Corps, numbered 174,000 men (in a total population of 134 million). There were constitutional objections to 'standing armies', considered a threat to democratic government.
But Americans were sufficiently alarmed by late 1940 for Congress to order selective conscription. All this merits saying because of the contemporary myth, promoted by the Bush administration in order to identify its policies with what Americans now call 'the Good War', that 'the Americans' freed Europe.
Few Americans today can imagine that the British and Canadian forces attacking across the Normandy beaches on 6 June 1944 outnumbered Americans by a third: 76,000 to 58,000. Last year, in the dispute over Nato versus EU allegiances, some Polish officials declared that while America had liberated Poland (from Russia), France and Britain had never done anything for Poland. The two had merely gone to war in 1939 because of Poland; if they had not turned Poland's conquest into the Second World War, Poland today might be German - or Russian.
Last week a normally astute French commentator outdid Hollywood itself in misappropriating British (and Polish) feats to American advantage, attributing to 'the Americans' the Mulberry artificial harbours, Enigma intercepts of German communications, the Dieppe raid of August 1942, and the great disinformation campaign that caused the Germans to hold forces back from the Normandy front, in fear of new landings in Pas de Calais. He wanted to describe the American arrival in Europe as from a new and more advanced world; as a revolutionary event, delivering a shock comparable to that given to dynastic Europe by France's revolutionary armies, bringing with them the republican idea - after which nothing would be the same.
But while the American army gave a cultural shock to Europe, it was initially only one of popular culture and democratic manners. The Americans of 1944 and 1945 were determined to go home. Soldiers had not enjoyed chilly and cramped Britain, disliked the French and, while they respected the Germans, had no desire to settle down with them. Popular pressure for demobilisation was enormous.
Defence expenditure in the last year of the war was $45 billion. In the first year of peace the budget was a quarter of that. Conscripted service legally was the war's duration plus six months. It had to be extended piecemeal until 1947. The army was coming apart. By the time of the Communist coup in Czechoslovakia in early 1948, when the Cold War began in earnest, there were only one-and-a-third army divisions remaining in the continental United States.
Those overseas, occupying Japan and Germany, were by then lackadaisically trained and unmotivated. When the Korean War broke out in June 1950, the two divisions first rushed to Korea from Japan were overrun almost as rapidly as they arrived. The commanding general of the first of them was captured fighting as a rifleman. Only Douglas MacArthur's Inchon landing, using troops and called-up reserves from the US, reversed the situation.
In 1945 the great popular fear was that peace would bring back the Depression. Unemployment in 1940 had been 14.6 per cent. At the peak of the depression, in 1932-33, a third of the labour force had been unemployed. What would happen when war orders to factories stopped, and the 16 million servicemen and women were back on the job market? Demand for homes and consumer goods, and social and demographic transformations war had produced, confounded those fears. The so-called GI Bill of Rights sent millions into higher education they would never otherwise have had.
The Cold War, not the Second World War, overturned the domination that isolationist sentiment had exercised during America's history, since George Washington had warned the nation against 'permanent alliances with any portion of the foreign world', and Thomas Jefferson had urged 'peace, commerce, and honest friendship with all nations, entangling alliances with none'.
America's transformational impact on Europe was caused by the Cold War, because this time the US, under threat, made a huge institutional commitment to Europe and its security.
The Marshall Plan came first, after Truman officials travelling in Europe during the terrible winter of 1947 reported penury and chaotic political conditions, with a threat of Communist coups in Italy and France. The aid offer was conditional on inter-European co-operation to plan how grants should be used. This was the precedent for the Council of Europe a year later, and later the European Union.
In March 1948, Britain, France and the Benelux countries signed the Brussels Treaty, to provide collective defence. A year later the North Atlantic Treaty incorporated other West Europeans and the two North American powers to form Nato. However, the Republican leader in the US Senate, Robert Taft, opposed Nato because it involved unforeseeable commitments (adding - bizarrely enough, in the light of today's Republican positions - that peace ultimately depended on 'international law... international courts... and joint armed force to enforce that law and the decisions of that court').
With Nato, the US was committed to Europe's permanent defence. However, the old isolationism still was not dead. It eventually made itself felt in an effort to export not only American values but also control. Only with control of the political and military environment could the nation hope again to be secure, as it had been in isolation.
The Normandy landings determined the way in which the Second World War ended, but not the outcome itself. That had been settled at El Alamein in 1942 and Stalingrad in 1943. Germany had been forced into retreat. Had the landings failed, the war would have been prolonged but not lost. The fire bombs would have been followed by nuclear bombs. That was not an outcome on anyone's mind on that June day 60 years ago.