government. Their leader, Brigadier General Venancio Flores, a caudillo and an early proponent of fusionism, found himself without sufficient military resources to mount a sustained revolt and resorted to asking for intervention by Argentina. Argentina was a fragmented nation (since the 1852 downfall of Argentine dictator Juan Manuel de Rosas), with the Argentine Confederation and the State of Buenos Aires each vying for supremacy. Flores approached the Buenos Aires Minister of War, Bartolomé Mitre, agreeing to throw the support of the Colorados behind Buenos Aires in exchange for subsequent Argentine assistance in their fight against the fusionist government in Montevideo (the Uruguayan capital). Flores and his Colorado units served Buenos Aires with fierce determination. They played a decisive role in the Battle of Pavón on 17 September 1861, in which the Confederation was defeated and all Argentina was reunited under the government in Buenos Aires. In fulfillment of his commitment, Mitre arranged for the Colorado militia, Argentine volunteer units and supplies to be carried aboard Argentine vessels to Uruguay in May and June 1863. Ships of the Argentine navy kept Uruguayan gunships away from the operation. Back on his native soil, Flores called for the ouster of the constitutional government, by that time headed by Bernardo Berro. Flores accused the Montevideo government of Blanco sympathies and framed his "Liberating Crusade" (as he called his rebellion) in the familiar terms of a Colorado vs. Blanco struggle. Colorados from rural areas joined defectors from the military in responding to his call. International crisis Paraguayan–Blanco ties Although the Colorados had defected to the Flores insurgency, the national guard continued to support the fusionist government. Blanco partisans filled its depleted ranks. They also replaced army officers who had deserted to Flores. The Blancos received aid from several Argentine Federalists who joined their cause. As in Uruguay, Argentina had long been a battleground of rival parties, and Bartolomé Mitre's victory at Pavón in 1861 had signaled the triumph of his Unitarian Party over the Federal Party led by Justo José de Urquiza. Mitre denied any involvement in the Flores rebellion, even though his complicity was widely known and taken for granted. Relations between Argentina and Uruguay worsened, and both nations came close to declaring war on each other, although neither could afford a direct military conflict. Argentina had only recently emerged from a long civil war, and was still struggling to suppress a Federalist rebellion