The Battle of Dien Bien Phu was the decisive engagement in the first Indochina War (1946–54). After French forces occupied the Dien Bien Phu valley in late 1953, Viet Minh commander Vo Nguyen Giap amassed troops and placed heavy artillery in caves of the mountains overlooking the French camp. Boosted by Chinese aid, Giap mounted assaults on the opposition’s strong points beginning in March 1954, eliminating use of the French airfield. Viet Minh forces overran the base in early May, prompting the French government to seek an end to the fighting with the signing of the Geneva Accords of 1954.
The battle that settled the fate of French Indochina was initiated in November 1953, when Viet Minh forces at Chinese insistence moved to attack Lai Chau, the capital of the T’ai Federation (in Upper Tonkin), which was loyal to the French. As Peking had hoped, the French commander in chief in Indochina, General Henri Navarre, came out to defend his allies because he believed the T’ai “maquis” formed a significant threat in the Viet Minh “rear” (the T’ai supplied the French with opium that was sold to finance French special operations) and wanted to prevent a Viet Minh sweep into Laos. Because he considered Lai Chau impossible to defend, on November 20, Navarre launched Operation Castor with a paratroop drop on the broad valley of Dien Bien Phu, which was rapidly transformed into a defensive perimeter of eight strong points organized around an airstrip. When, in December 1953, the T’ais attempted to march out of Lai Chau for Dien Bien Phu, they were badly mauled by Viet Minh forces.
Viet Minh commander Vo Nguyen Giap,with considerable Chinese aide, massed troops and placed heavy artillery in caves in the mountains overlooking the French camp. On March 13, 1954, Giap launched a massive assault on strong point Beatrice, which fell in a matter of hours. Strong points Gabrielle and Anne-Marie were overrun during the next two days, which denied the French use of the airfield, the key to the French defense. Reduced to airdrops for supplies and reinforcement, unable to evacuate their wounded, under constant artillery bombardment, and at the extreme limit of air range, the French camp’s morale began to fray. As the monsoons transformed the camp from a dust bowl into a morass of mud, an increasing number of soldiers–almost four thousand by the end of the siege in May–deserted to caves along the Nam Yum River, which traversed the camp; they emerged only to seize supplies dropped for the defenders. The “Rats of Nam Yum” became POWs when the garrison surrendered on May 7.
Despite these early successes, Giap’s offensives sputtered out before the tenacious resistance of French paratroops and legionnaires. On April 6, horrific losses and low morale among the attackers caused Giap to suspend his offensives. Some of his commanders, fearing U.S. air intervention, began to speak of withdrawal. Again, the Chinese, in search of a spectacular victory to carry to the Geneva talks scheduled for the summer, intervened to stiffen Viet Minh resolve: reinforcements were brought in, as were Katyusha multitube rocket launchers, while Chinese military engineers retrained the Viet Minh in siege tactics. When Giap resumed his attacks, human wave assaults were abandoned in favor of siege techniques that pushed forward webs of trenches to isolate French strong points. The French perimeter was gradually reduced until, on May 7, resistance ceased. The shock and agony of the dramatic loss of a garrison of around fourteen thousand men allowed French prime minister Pierre Mendes to muster enough parliamentary support to sign the Geneva Accords of July 1954, which essentially ended the French presence in Indochina.