Part of a character's backstory in my novel involves him leaving Germany to get away from the persecutions of Jews in the late 30s, then getting caught by them soon after France surrenders in the wake of the World War, ending up in the Dachau concentration camp. All my research as of now led me to believe this scenario is historically accurate, but I ask here, for there are people way more educated in these matters, will I have to rewrite anything to fix any historical inaccuracy?
Not sure what it is you're asking here. Are you asking if the few facts you've given us in the first paragraph are accurate, or something else? I'm no historian, but providing your sources were fairly reliable (in other words as long as you didn't use Yahoo Answers) I see no reason why your facts should be doubted. As for having to make changes, we can't know that without seeing the entire back story, as it presumably includes far more detail that you've given us here.
I don't see anything incorrect in what little you've given us, though I don't know the exact timeframe when the the Nazi government began rounding up French Jews. Though I'll say you'll want to know exactly where your character settles in France, as that will determine who caught and deported him. Could be German occupation forces, could be the Vichy government.
I found this on Wikipedia, about Nice in WW2: As war broke out in September 1939, Nice became a city of refuge for many displaced foreigners, notably Jews fleeing the Nazi progression into Eastern Europe. From Nice many sought further shelter in the French colonies, Morocco and North and South America. After July 1940 and the establishment of the Vichy Regime, antisemitic aggressions accelerated the exodus, starting in July 1941 and continuing through 1942. On 26 August 1942, 655 Jews of foreign origin were rounded up by the Laval government and interned in the Auvare barracks. Of these, 560 were deported to Drancy internment camp on 31 August 1942. Due to the activity of the Jewish banker Angelo Donati and of the Capuchin friar Père Marie-Benoît the local authorities hindered the application of anti-Jewish Vichy laws.[12]