In his book, Lt. Gen. Davidson reports that near the end of the Battle of Dien Bein Phu, "3,000 to 4,000 men out of the 10,000 man garrison had become internal deserters, the so-called 'Rats of the Nam Yum,' who did not fight, but who did devour precious non-military supplies, particularly food."
On May 7, 1954, the Viet Minh made the final push into the main camp at Dien Bien Phu. It had been a particularly bloody firefight that ended by about 1730 hours. However, at firebase Isabelle, about 2 miles south of the main camp, the defenders attempted a night break out down the Nam Yum River. Most of the garrison was cut down in the valley, but 70 men made it out to French bases in Laos.
It was the beginning of the end of the French Empire. By the time they lost Algeria in 1962 it was all but over. The French have never regained their national pride.