The Battle of Pehuajó, also known as Battle of Corrales or Battle of Itati was fought during the Paraguayan War on 31 January 1866. Around 1,500 Paraguayan troops commanded by general Francisco Isidoro Resquín and lieutenant Celestino Prieto engaged in a surprise attack against a couple of advanced Argentine and Uruguayan battalions with about 2,000 men led by general Emilio Conesa, under direct command of the president of Argentina, Bartolomé Mitre. Previous events After the Brazilian siege and bombing of Paysandú (December 1864 - January 1865) Paraguay declared war on Brazil because of the Treaty both Brazil and Paraguay signed for "defending the Uruguayan independence" (though the validity of that treaty is still controversial) and for protecting the allied Uruguayan blanco government. After a victorious, but later abandoned campaign in Mato Grosso, the troops of Paraguayan president and field marshal Francisco Solano López were intending to reach Uruguay through the Entre Ríos province of Argentina. While president Mitre was secretly giving military support to the coup in Uruguay and allowing the Imperial Brazilian Navy and troops to pass through Argentine territory, he denied access to the Paraguayan Army, this led to the declaration of war from Paraguay to Argentina and the later Corrientes campaign. After several defeats of the Paraguayan Army in Corrientes (where general Wenceslao Robles refused to accomplish López's orders and advanced until dangerous positions very far from supply lines) and in Uruguaiana (where general Antonio de la Cruz Estigarribia by his own will entered in a trap, surrendering with 10,000 men), the Paraguayans had to retreat from Argentina after fierce battles with general Wenceslao Paunero and his men. Solano López declared Antonio de la Cruz Estigarribia a "traitor" and "spy of the enemies" (later, Estigarribia joined the infamous Paraguayan Legion) and replaced Wenceslao Robles for his well trusted general Resquín. The battle Paraguayan troops retreated to their own territory, protected by the . General Conesa, leader of the advanced allied forces, tried to chase the fleeing soldiers, but the attempt was very risky and allowed the Paraguayans to have good counter-attacking possibilities. Solano López understood this and sent small raiding parties of 100-200 men across the river to attack allied posts. Most notable were raid on 13, 16, 17, 19 and 25 January. On 29 January 1866, 400 Paraguayans crossed the River Paraná and drove the Argentines from Corrales (in the Argentine town of Paso de la