Justo José de Urquiza (hōō´stō hōsā´ ŧħā ōōrkē´sä), 1801–70, Argentine general and politician, president of the confederation (1854–60). As the caudillo of Entre Ríos prov., he helped sustain the power of Juan Manuel de Rosas. In 1851, resentful of the economic and political dominance of Buenos Aires, he revolted against his chief. Supported by Brazil and the Uruguayan liberals, he forced Manuel Oribe to capitulate, ending the long siege of Montevideo (Oct., 1851), and defeated Rosas at Monte Caseros (Feb. 3, 1852). Urquiza immediately began the task of national organization. He became provisional director of the Argentine confederation in May, 1852. A constituent assembly adopted (1853) a constitution based primarily on the ideas of J. B. Alberdi, and Urquiza was inaugurated president in Mar., 1854. In his administration foreign relations were improved, public education was encouraged, colonization was promoted, and plans for railroad construction were initiated. His work of national organization was, however, hindered by the opposition of Buenos Aires prov, which seceded from the confederation. Open war broke out in 1859. Urquiza defeated at Cepeda the provincial army led by Bartolomé Mitre (Oct., 1859), and Buenos Aires agreed to reenter the confederation. Constitutional amendments proposed by Buenos Aires were adopted in 1860. The settlement was short-lived, and further difficulties culminated in civil war. Urquiza met the army of Buenos Aires, again led by Mitre, at Pavón (Sept., 1861). The battle was indecisive, but Urquiza withdrew from the field, leaving the victory with Mitre. He retired to Entre Ríos, where he ruled with patriarchal autocracy until his assassination.