incorporation

CONT: As to Alsace-Lorraine, the German Law of 9 June 1871 ... for their incorporation into the German Reich expressly declared that the entry into force of the German Constitution there would be delayed until 1 January 1873.
OBS: The term [collective naturalization is] often used for the process whereby the inhabitants of an area, which is incorporated into the territory of a state and therefore comes under its sovereignty, acquire the nationality of that state.