State of Buenos Aires

The State of Buenos Aires was a short-lived secessionist republic in present-day Argentina. It was proclaimed on 11 September 1852, when Buenos Aires Province rejected the San Nicolás Agreement and refused to accept the authority of the Argentine Confederation led by Justo José de Urquiza. The province kept its own government, constitution and customs house, the main source of public revenue, and no foreign power formally recognised the breakaway state. Buenos Aires was besieged by Confederation forces in 1853, but the siege was lifted and the state survived. Its leaders, including Bartolomé Mitre, pressed for a new national constitution that would give the province a dominant role. In 1859 the Confederation defeated Buenos Aires at Cepeda, and the 1860 Pact of San José de Flores began reunification. Mitre's victory at the Battle of Pavón in September 1861 ended the secession, and Buenos Aires rejoined the Argentine Confederation, which was reorganised as the Argentine Republic in 1861-62.