What happened 1952AD in Vietnam

The Việt Minh launched attacks on Hòa Bình, forcing the French to withdraw back to their main positions on the De Lattre line by February 22, 1952.

In the Battle of Nà Sản, starting on October 2, French commanders began using "hedgehog" tactics, consisting in setting up well-defended outposts to get the Việt Minh out of the jungle and force them to fight conventional battles instead of using guerrilla tactics.

On October 17, 1952, Giáp launched attacks against the French garrisons along Nghĩa Lộ, northwest of Hanoi, and overran much of the Black River valley, except for the airfield of Nà Sản where a strong French garrison entrenched.

On October 29, 1952, in the largest operation in Indochina to date, 30,000 French Union soldiers moved out from the De Lattre line to attack the Việt Minh supply dumps at Phú Yên.

Salan took Phú Thọ on November 5.

Salan took Phu Doan on November 9 by a parachute drop.

Salan took Phú Yên on November 13.

Salan correctly guessed what the Việt Minh were up to and cancelled the operation on November 14, beginning to withdraw back to the De Lattre Line.

The only major fighting during the operation came during the withdrawal, when the Việt Minh ambushed the French column at Chan Muong on November 17.