World Powers meet in 1954 in Geneva, Indochina is on the table. France and the Viet Minh both understand that whoever wins the next big battle is gonna have all the power at the bargaining table. The french find the best valley to run a gauntlet to smash the peasants. The french ignore the big mountains around them because there is no way they could be a threat and aim their cannons towards the gauntlet. Viet Minh push 50000 soldiers, dissassambled artillery, cannons and all the food need for a siege and the quarter million of human road to push all of this up into the mountains. The Viet Minh open fire. The French artillery commander Charles Piroth who said before the fight "I have more guns than I need", took the pin off a grenade in his tent and hugged it.
Viet Minh had a very good position at the table in Geneva.