Date with destiny

His telling answer: “We have to be careful . . . that we do not press the French to the point where they say, ‘All right, take the damned country, we don’t want it.’ ’’

This long-forgotten but fateful exchange in a Capitol Hill hearing room, recounted in Ted Morgan’s “Valley of Death,’’ set the stage for the calamitous battle of Dien Bien Phu, which itself set the stage for the American appointment in Vietnam. In many ways this exchange represents the hinge of Morgan’s 752-page, panoramic history of war in Vietnam before Americans fought their own Vietnam War.

Only 26 days after Green pressed Acheson on Indochina, Truman signed NSC 64, setting forth the principles behind the Domino Theory, suggesting that if the “combined native Indochinese and French troops’’ didn’t contain Ho Chi Minh, then “the neighboring countries of Thailand and Burma could be expected to fall under Communist domination.’’ And precisely a week later, Truman approved $10 million in military aid for Indochina, beginning with a handful of C-47 Dakota aircraft and a load of Jeeps.

“At this point,’’ Morgan writes, “the tragedy of Indochina became the shared responsibility of the French and the Americans.’’

But long before Vietnam and America would be inextricably linked in the great drama of the 1960s and the 1970s, French forces would be defeated in perhaps the most furious battle of the postwar world, a bloody and bitter struggle and siege lasting more than a month and a half. In its aftermath, the French would depart; Vietnam would be divided; and eventually aggression by the communist north against the south would lead to American involvement.

For a generation, the 1954 struggle at and around Dien Bien Phu has been an obscure but dark cloud in the Cold War narrative, a debacle whose drama was, curiously, almost forgotten by a generation that knew but did not understand how the French preceded the Americans in the Indochina adventure and how Vietnam came to be divided at a Geneva conference table. Morgan has rectified that, producing an electrifying and poignant look at one of the great turning points in history, a moment when an Asian independence movement mortified an established European fighting force and upended a colonial social order.

Morgan, who is French, sketches an evocative portrait of colonial France in Indochina in the years after World War II, an era when more than 82,000 soldiers were garrisoned in more than 900 posts, a few without radio link, a handful with a ration of only 45 shells a month. In the cities, there was fine wine, fine dining, even dancing. Canned white asparagus was not unknown.

Mining regimental memoirs, letters, and personal reminiscences along with the accounts of the Vietminh in newly opened archives in Hanoi and newly released message traffic from the Soviet and Chinese diplomats in Geneva, Morgan sets out a battle that lasted 14 times as long as Gettysburg and was so ghastly that Bernard B. Fall captured the horror in the six words that constituted the title of his 1967 account: “Hell in a Very Small Place.’’

This will tell you how dreadful was the battle at Dien Bien Phu, the French fortification surrounded by mountains, some 6,000 feet high, and situated in a valley no wider than the distance from the East River to the Hudson: The Vietminh, who vastly outnumbered their French opponents, poured into battle as if their number were unlimited. The French were sitting ducks. Their medical bandages were infested with maggots; the plaster casts applied to the wounded could not dry. Amputees sat behind machine guns, loading ammunition handed to them by other amputees.

But Morgan’s volume is not simply a military history. It also sets forth the diplomatic dance, the worried conferences in Washington, London, and Paris, the tension-filled negotiations in Geneva, the vague talk about the introduction of atomic weapons, all of the hostility, mistrust and strains of the Cold War, drenched in a colonial marinade.

This crisis and challenge threw Washington into a quandary long before it became ensnared in a quagmire. “Since France was doing nothing to recognize the legitimate political aspirations of the Vietnamese, the United States did not wish to help them prosecute a colonial war,’’ Morgan explains. “However the United States needed a friendly France in pursuit of America’s aims in Europe.’’ Those aims were to establish a bulwark against communism in the years after World War II — a goal that dovetailed nicely with the French struggle against Ho and the Vietminh. American policy seldom has been such a wretched, confusing mess.

Once Dien Bien Phu fell, so did the notion that colonial rulers could keep communists at bay, even if, as historians would come to conclude, the Vietminh were more nationalists than Marxists. A front-page editorial in a French daily the day after the garrison fell captured the French tragedy and tragically adumbrated the American disaster in Southeast Asia:

“The men of Dien Bien Phu died because we lied to ourselves,’’ wrote the editors of Le Figaro. “They died because we did not know how to fight this war and because we were incapable of not fighting it.’’

David M. Shribman, for a decade the Globe’s Washington bureau chief, is executive editor of the Pittsburgh Post-Gazette.