On July 5th, 1830, Dey Husayn surrendered. The French army took over Ottoman Algiers, and, mechanically, Algerians were said to be French. This automatic granting of French nationality emanated from a general principle of the law: the annexing state grants its nationality to the subjects whose state disappears as an object of international law. In the paper, I will discuss this a priori of the law by comparing it with both the legal production and the claims to nationality undertaken by Algerians residing in the Ottoman Empire. How did colonial subjects rebuild their lives in the Ottoman Empire after the colonization of their homeland ? How did theses imperial subjects negotiate their reassignment to the Ottoman Empire by drawing on their multiple affiliations? How did the memory of French colonial violence impact their conception and practices of nationality ? The question of the nationality can be considered as a legal device used to fight the colonial war by other means. Taking advantage of this competition between states, Algerian emigrants invite us to examine the issue of nationality in a way that transcends the nation-state paradigm. They also highlight the nationality law as a narrative of violence. Verbatim records of consular interviews, registration on nefous (i.e. civil status registers), rabbinical proofs of origin and certificates of notoriety issued by qadi, notarial documents, this vast array of sources, including forged documents, underlines the articulation of law, history and daily life in a global microhistory perspective.