Juan Manuel de Rosas was an Argentine politician and military leader who served as the governor of the province of Buenos Aires during the 19th century. He held power in two main periods, from 1829 to 1832 and again from 1835 to 1852. Rosas is known for his authoritarian rule and his efforts to centralize power in Argentina. Rosas was a key figure in the conflict between the Unitarians, who sought a centralized government, and the Federals, who supported provincial autonomy. His regime was marked by political repression and the use of violence against opponents, which ultimately led to his downfall and exile after the defeat in the Battle of Caseros in 1852.