Glad he made it out of there. Sad that such things ever happened. Even sadder that those things are slowly being forgotten.

That is an interesting family history tale.

What camp was Cousin Jules in?
Was he a strongly anti-Nazi resister that he was kept in a camp for the whole war?
How did he know that all the guards at both camps were killed?  Did he have contact with fellow unit members after his release?

From my admittedly cursory and incomplete readings on the subject, it seemed that most of the French POWs taken in 1940 (some 1.8 million of them) had either been released or were working as forced farm laborers in Germany.  Certainly, I do not want to accuse your uncle or Cousin Jules of telling false tales, but sometimes stories get garbled up over the years, especially a tale 70 years old which may have been passed on with 2nd or 3rd hand information.


From a wiki article:
https://en.wikipedia.org/wiki/French_prisoners_of_war_in_World_War_II


"Most French prisoners of war were not held in camps for most of the war, but instead, over 93 percent of French prisoners of war lived and worked on Kommandos of work details.[17] Under the terms of the Geneva Convention NCOs were, like officers, exempted from work during captivity, but Germans often forced them to work. Workers were fed but virtually their entire wages were paid directly to the German army and prisoners were only allowed to retain 70 pfennigs per day.[27]

Work Kommandos were very variable, but those in agriculture were generally considered better than ones in factories or mining, where conditions were worse and prisoners were vulnerable to Allied bombing raids.[28] In rural areas of Germany, French prisoners replaced locals conscripted into the German army as agricultural labourers.[28] Guarding Kommandos was difficult, meaning that, in practice, prisoners were allowed a wider measure of freedom compared to the camps. They were often viewed with curiosity by the German rural population, and the French prisoners were often allowed to mix quite freely with German civilians.[27] Although unlawful, many French prisoners began relationships with German women."


And from another article:

"Four main POW groups can be distinguished based on Germany’s adherence to the Geneva Convention. British and American POWs received treatment mostly complying with the Geneva Convention. French and Belgians could suffer from arduous conditions but on average were treated fairly well; Yugoslavs and IMIs only encountered partial compliance; Poles and Soviets possessed no legal protection whatsoever. Initially, most POWs worked in agriculture, but by 1944, they were increasingly employed in coal mining and the munitions industries. Also, the ideological discrimination largely determined work allocation. While for instance half of all French POWs worked in agriculture in 1944, three quarters of the Soviet POWs worked in industry."

http://www.voxeu.org/article/exploiting-enemy-economic-contribution-prisoners-war-nazi-germany