“1st Indochina War? I'm pretty sure they were pretty decisively defeated at Dien Bien Phu.”: What: 12,000 men lost for the French…: Few battalions of Paratroopers, Foreign Legion and Colonials?
The Vietminh lost between 20,000 and 30,000 men, their elite divisions (308 and 312) decimated. But the French saw the danger and didn’t go for “a last push and” so decided not to sent reinforcement but to negotiate. And they did it in telling Ho Chi Minh that a prolongation of the war would see the draftees, so will raise the number of French Soldiers around 2,000,000.
It was decisive just because the French Government was decided to go.
If you want to compare with the lost in the Ardennes in 1944…

The decisive defeat for the French is the battle of Cao Bang, That Khe, Dong Khe, Lang Son and the lost of the RC4 that will give to the Vietminh a direct access to China just fallen in Mao’s hands.
Dien Bien Phu was just a good pretext for the new French Government to cut and run.

Now, about some comments I read: When, long time ago, I was a professional soldier, my comrades in arm and I were laughing at the US Army, enable to go on the field without their coca, having their shower heliported every evening and refusing to walk more than 500 metres…

I remember some training; it was unbelievable to see a US soldier just putting the barrel of his gun in the ground, helmet on the top and starting a nap… The look of my soldiers (draftees) was something to see…

The US army probably rectified this, but really…

About Africans, the best troops in the French Colonial were African. The big surprise at Dien Bien Phu was the collapse of the Moroccans of the 4th RTM, veterans of the Campaign of Italy…
The Colonial Powers used a lot of their Colonials to fight as they were highly regarded for their military capacities…