Justo José de Urquiza (October 18, 1801 - April 11, 1870) was an Argentine general and politician. He was president of the confederation from 1854 to 1860.
As the caudillo of Entre Ríos, Urquiza helped sustain the power of 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 in October 1851, finally defeating Rosas in February 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 Juan Bautista Alberdi, and Urquiza was inaugurated president in March 1854.
During 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, which seceded from the confederation. Open war broke out in 1859. Urquiza defeated the provincial army led by Bartolomé Mitre in October 1859, and Buenos Aires agreed to re-enter the confederation.
Constitutional amendments proposed by Buenos Aires were adopted in 1860 but the settlement was short-lived, and further difficulties culminated in civil war. Urquiza met the army of Buenos Aires, again led by Mitre, September 1861. The battle was indecisive, but Urquiza withdrew from the field, leaving the victory with Mitre. He retired to Entre Ríos, where he ruled until he was assassinated at age 69.