Who was Juan Manuel de Rosas, and why did Giuseppe Garibaldi fight against him?

Juan Manuel de Rosas (1793–1877) was a powerful military and political leader who served as the governor of Buenos Aires, Argentina, from 1835 to 1852. Although he claimed to be a federalist, his 17-year rule was a centralist dictatorship characterized by the use of a ruthless secret police force known as the Mazorca to intimidate and suppress all political opposition.1

Giuseppe Garibaldi fought against Rosas because he was deeply committed to the cause of liberty and became involved in the internal conflicts of the Río de la Plata region during his South American exile. In 1842, Garibaldi was placed in charge of the Uruguayan navy to defend the nation against the forces of Rosas, who was supporting the Blanco Party in their siege of Montevideo. Garibaldi’s service in this conflict, including his command of the Italian Legion, provided him with essential training in guerrilla warfare that would later define his revolutionary career in Europe.23