On October 24, 1870, The French government issued a decree to recognize the Jews of Algeria as French citizens. The law had been written and passed after much campaigning by powerful French Jews such as Adolphe Crémieux.
By the eighth century, North Africa was under Arab rule and the population had mostly converted to Islam. Under Islamic law, Jews and Christians were dhimmis, meaning they were “residence in return for (sometimes extremely high) taxes.” They were granted this status as monotheists and were what one might call “second-class citizens.” Algeria generally remained under Islamic control, until 1830, when the French began their conquest of the region.
The Jewish community welcomed French rule and often helped the French administration, for instance, by serving as translators. But, French rule was a double-sided coin for them. On one hand, the French were more friendly to the Jews and Christians than to the natives. On the other hand, the French limited the Jewish courts to only officiate over marriages, divorce and liturgy (and eventually not even that), whereas before, the Jewish community had been autonomous.
Although the intentions of the Crémieux Decree were noble, it caused the Jews of Algeria to become isolated even further from their neighbors. Additionally, many of the French were themselves anti-Semitic. Over the next decades there developed anti-Semitic political parties, and, from time-to-time, riots broke out against the Jews.
In World War II under Vichy, the French settlers who had always resented the Jews took their revenge. In fact most of the members Resistance in Algeria before the Americans arrived were Jews. The American forces used them to smooth the landing and then abandoned them when things got difficult.