Moreno, Mariano (märyäˈnō mōrāˈnō) [key], 1778–1811, Argentine revolutionist and publicist. He became prominent as legal counselor to the royal audiencia and to the cabildo of Buenos Aires. His condemnation of the Spanish colonial system and his advocacy of liberal economic principles attracted attention. A leader in the revolution of May, 1810, which deposed the Spanish viceroy, he was secretary of the first revolutionary governing junta and exerted a significant influence. He founded (June 7, 1810) the Gazeta de Buenos Aires and, as editor, championed in its columns his democratic, reform ideas. In 1810 he founded the national library. His liberal policy provoked a conflict with the conservatives, who, in spite of Moreno's opposition, admitted provincial deputies to the junta; Moreno resigned (Dec., 1810). His resignation checked the democratic movement in the Río de la Plata and initiated a protracted struggle between Buenos Aires and the country provinces. Appointed to a diplomatic mission abroad, he sailed for Europe (Jan., 1811) and died at sea.