The battle of Dien Bien Phu was a fierce battle lasting 170 days between the French Expeditionary Corps and the Viet Minh.
The battle was a response to the French attempt to occupy Dien Bien Phu. Operation Castor began on November 20, 1953. With a large air drop of French troops into the valley and the construction of protected air strip.
Despite French attempts to destroy supply routes and feed false information to the enemy over the coming weeks, the Viet Minh built up a mass of artillery and forces around the base.
By the end of the battle the French reported losses of 2,293 men KIA, whilst the North Vietnamese suffered 10 times as many losses.
On May the 1st, the French managed to fight off large scale attack that was launched against their exhausted troops. However, after continual attacks, on May 7th General Giap ordered the final assault, and by nightfall all French positions had been taken and Dien Bien Phu had fallen.