With French supply lines interrupted, the French position became untenable, particularly when the advent of the monsoon season made dropping supplies and reinforcements by parachute difficult. With defeat imminent, the French sought to hold on until the opening of the Geneva peace meeting on April 26. The last French offensive took place on May 4, but it was ineffective. The Việt Minh then began to hammer the outpost with newly supplied Soviet Katyusha rockets and other weaponry provided by communist allies.
The final fall took two days, May 6 and 7, during which the French fought on but were eventually overrun by a huge frontal assault. General Cogny, based in Hanoi, ordered General de Castries, who was commanding the outpost, to cease fire at 5:30 pm and to destroy all materiél (weapons, transmissions, etc.) to deny their use to the enemy. A formal order was given to not use the white flag so that the action would be considered a ceasefire instead of a surrender. Much of the fighting ended on May 7; however, the ceasefire was not respected on Isabelle, the isolated southern position, where the battle lasted until May 8, 1:00 am.
On 7 May 1954, the French garrison at Dien Bien Phu surrendered. The defeat marked the end of French military involvement in Indochina. At the Geneva Conference, the French negotiated a ceasefire agreement with the Viet Minh, and independence was granted to Cambodia, Laos, and Vietnam.
In 1954, after the crushing defeat of French Union forces at Battle of Dien Bien Phu, 2300 French soldiers died during the Battle of Dien Bien Phu more than 10000 french soldiers have surrendered to Vieth Minh. France gave up its fight against the Việt Minh, losing 70,000 soldiers from the eight years of the First Indochina War.
When the French fortress of Dien Bien Phu fell to the Vietnamese Communists in May 1954, Eisenhower refused to intervene despite urgings from the Chairman of the Joint Chiefs, the Vice President and the head of NCS.