Unitarianists or Unitarians were the proponents of the concept of a unitary state in Buenos Aires during the civil wars which shortly followed the Declaration of Independence of Argentina in 1816. They were opposed to the ArgentineFederalists, who wanted a federation of independent provinces. In the Argentine War of Independence the forces of the United Provinces of the Río de la Plata fought Spanish royalists who attempted to regain control of their American colonies after the Napoleonic Wars. After the victorious May Revolution of 1810, disagreements arose between the dominant province of Buenos Aires, who were known as Unitarianists, and the other provinces of Argentina, known as the Federalists. These were evident at least as early as the declaration of Argentine independence in 1816. The Unitarianists lost their controlling power after the Battle of Cepeda, which was followed by several months of chaos. However, the Unitarianists were forced to sign a treaty with other provinces. This did not solve the conflicts between the Federalists and the Unitarians. Under PresidentBernardino Rivadavia, the Unitarianists gained control for a short period of time. The Constitution of 1826 allowed for a balance between the ideas of the Unitarianists and the Federalists: “It provided for a centralized national authority while leaving the provinces with considerable local powers.” However, the constitution was rejected by provincial caudillos, military leaders, and the conflict continued. Forced to resign, the Government of Buenos Aires and the Foreign relations of the country were taken over by Federalist Manuel Dorrego. However, a contingent of military led by Juan Lavalle, opposed to the peace negotiations with the Brazilian Empire after the end of the Cisplatine War took over the Buenos Aires Government and shot Dorrego at Navarro. In 1829, Juan Manuel de Rosas, the leader of a troop of Federalists, became the Governor of Buenos Aires after defeating General Juan Lavalle, who was then forced into exile. Although Rosas was a Federalist, his following of the principles of Federalism has often been questioned. In 1830, the Unitarian League was created by General José María Paz in order to defeat the Federalists. The Federalists faced Paz and his troops on May 31, 1831 and the Unitarianists were defeated after the Gauchos captured the Unitarianist commander. The Provinces of the Unitarian League gradually joining into the Federal Pact and the Argentine Confederation. Although the Unitarians exiled in neighboring countries, the Civil War would continue for another two decades, the Unitarians being led by Lavalle, Paz, Lamadrid, and many others. With support from Corrientes Province and the Brazilian Empire, Justo José de Urquiza, Federalist caudillo of Entre Ríos Province, finally defeated Rosas at the Battle of Caseros on February 3, 1852. On May, the San Nicolás Agreement was signed by the provincial governors. The pact reinstated the 1831 Federal Pact original provisions for a constitutional convention. In 1853 the Autonomists of Buenos Aires broke away from the Argentine Confederation after Urquiza nationalized the customs receipts from Buenos Aires and allowed the free flow of trade on the Parana and Uruguay rivers. In 1859 Buenos Aires was forced to accept the federal constitution of 1853 after six years of secession, after Mitre was defeated at the 1859 Battle of Cepeda by Urquiza. However, the federal constitution was "amended to allow Buenos Aires greater influence" after the ensuing 1861 Battle of Pavón. Mitre was then chosen as President of a new national government. Opposition to the Unitarianists continued until 1890 under the Córdoba League.
