The Tamoio War, also known as the Tamoio Confederation – both terms being historiographically contested – was a multi-layered conflict that unfolded along the southeastern coast of Brazil from the mid-1550s, perhaps earlier, until 1575. Above all, it was a movement of Indigenous resistance to the growing Portuguese presence, manifested through the occupation of Indigenous lands, colonial settlement, evangelization, and enslavement. Its main protagonists were a shifting coalition of Tupinambá groups, collectively known as Tamoios, whose territories extended between Bertioga and Cabo Frio. This resistance became intertwined with longstanding rivalries and warfare among Indigenous nations, particularly those opposing the Tupinambá to the Tupiniquim and Temiminó, whom the Portuguese enlisted as allies. In 1555 the French established themselves in Guanabara Bay as the base of their France Antarctique project. This added a third layer to the conflict, intensifying it and altering the balance of forces: the French allied with the Tamoios, while their presence encouraged the Portuguese to accelerate their conquest and colonization of the region. After several episodes of conflict, a Jesuit mission to Iperoig in 1563 temporarily secured a peace agreement with some Tamoio groups, but fighting soon resumed. The conflict culminated in the Portuguese campaigns of 1566-1567, in which forces led by Estácio de Sá, supported by the Temiminó leader Arariboia, defeated the Franco-Tamoio forces at Uruçumirim and elsewhere in Guanabara, consolidating Portuguese control, including the newly founded city of Rio de Janeiro. Surviving Tamoios then moved to Cabo Frio, where a Portuguese expedition in 1575 finally broke their resistance, reportedly followed by the massacre and enslavement of thousands of Indigenous.