The transition from monarchy to republic in Brazil was catalyzed by a military coup led by Marshal Deodoro da Fonseca. Tensions had been mounting for several years due to a combination of political dissatisfaction and economic instability. The Brazilian monarchy, under Emperor Pedro II, faced growing opposition from various military and civilian factions who were increasingly disillusioned with royal governance and sought democratic reforms. Following a series of protests and political maneuvering, the military declared a coup on November 15, 1889, effectively deposing the emperor, who had ruled since his childhood.

Following the coup, Deodoro da Fonseca assumed leadership as the provisional president of Brazil. The declaration of the republic was a pivotal moment in Brazilian history, as it marked a definitive break from the imperial system that had governed the country since its independence from Portugal in 1822. The new republican government adopted a more democratic constitution, emphasizing civil rights and electoral reforms. This shift also signaled the beginning of a turbulent period characterized by political instability and power struggles among various factions.

The implications of the coup were profound, as Brazil embarked on a path of republicanism that would redefine its political, social, and economic landscape. The military's involvement in politics laid precedents for future coups, and the need for modernization and reform became central themes in subsequent Brazilian politics. Over the next several decades, Brazil grappled with issues related to governance, social justice, and the rights of its diverse population as it continued to adjust to its new republican framework.