Rosas faced a difficult military threat during first years of his second administration. First, the Peru–Bolivian Confederation in the North declared the War of the Confederation against Argentina and Chile. Then, France made diplomatic requests which were denied by Rosas and subsequently imposed a naval blockade as a result. France invaded Martín García island and deposed the Uruguayan president Manuel Oribe, appointing instead the loyal Fructuoso Rivera, who declared war on Argentina in support of France. Domingo Cullen, from Santa Fe, promoted the secession of all provinces, leaving Buenos Aires alone in the conflict. Berón de Astrada, from Corrientes, opposed Rosas as well, and Juan Lavalle organized an army to take Buenos Aires. The ranchers mutinied in Chascomús and organized the "Freemen of the South" militia.