In the Paraguayan War, the Battle of Yatay was fought on August 17, 1865, between the troops of the Triple Alliance (Argentina, Brazil and Uruguay) and the soldiers of Paraguay near Paso de los Libres, Corrientes, Argentina. The Battle of Yatay was the first major land battle of the Paraguayan War, and most important of the war's second phase. Background Following the declaration of war by Paraguayan president Francisco Solano López on Argentina, the Paraguayans immediately attacked with two columns. The original plan was that the first column, commanded by Wenceslao Robles, would seize the town of Corrientes while a second column of 12,000 men, commanded by Antonio de la Cruz Estigarribia, would then advance to the east of Corrientes and capture Brazilian possessions on the Uruguay River. The primary focus of this invasion plan was the capture of Brazilian possessions, as this would prevent Brazilian expansion, a great concern of president López. The other column would then capture Corrientes, distracting Argentine forces and creating a lifeline between Paraguay and the Atlantic Ocean. This plan was later revised so that two-thirds of the assault force would attack Corrientes and later divert southeast and invade Uruguay. In response, a military alliance was signed on 1 May among Argentina, Uruguay and the Empire of Brazil. Following the successful capture of Corrientes by the Paraguayans, Argentine general Wenceslao Paunero launched a daring attack – on 25 May – that recaptured the city. However, given the numerical superiority of the Paraguayans, Paunero chose to evacuate the city and its civilians two days later and head to the southwest of the province. Only after having evacuated Corrientes did Paunero learn that the Paraguayans were advancing on the Uruguay River. Argentine president Bartolomé Mitre put general Justo José de Urquiza, governor of the province of Entre Ríos, in charge of facing the Paraguayan column. Urquiza called on his aid Paunero, who had retreated to Esquina. These forces were joined by a battalion of volunteers from Corrientes, led by colonel Desiderio Sosa, who had participated in the reconquest of Corrientes. Many future heroes of the Corrientes province, such as Santiago Baibiene and Plácido Martínez, were in that battalion. Meanwhile, the naval Battle of Riachuelo took place. During the course of the battle the Imperial Brazilian fleet destroyed the Paraguayan squadron near the city of Corrientes. This loss prevented the Paraguayan column on the Paraná River from providing