First Battle of Tuyutí

The First Battle of Tuyutí was a Paraguayan offensive in the Paraguayan War. The allied victory added to the Paraguayan troubles that began with a failed offensive and continued with the loss of its fleet in the Battle of Riachuelo.

In early May 1866, a Paraguayan attack at a marsh called Estero Bellaco failed. As the allies camped for over two weeks before resuming their advance, Paraguayan leader Francisco Solano López ordered a May 24 surprise attack on Tuyutí, a "a swampy, scrub-brush savannah".

The Paraguayans attacked in three columns, and soon the battle turned into "a series of charges and countercharges, a Latin American version of Waterloo". The Paraguayan columns continued to attack, but never could overcome the allied firepower.

Tuyutí was the last major Paraguayan attack. Ultimately, it was a devastating Paraguayan defeat: of the 6,000 men wounded after the battle, a large percentage would die subsequently. The Paraguayan military was decimated.

The May 24, 1866 battle of Tuyutí is known as the First Battle of Tuyutí; the second battle occurred on November 7, 1867, and was an indecisive and less consequential battle in which each side lost about 2,400 men.

Battle description
From a small hill, with President Lopéz himself commanding the troops, the Paraguayans prepared for a decisive battle. Twenty-four thousand Paraguayans, hoping for the destruction of the allied forces, attacked at midday on May 24 after a rocket announced the order, and the battle began. Lopéz tried to circle the allies with two strong wings as his center forced them to hold positions. His left faced the Argentines, while the Uruguayans were in the center with the Brazilians and engaged the right wing. The terrain was not suitable for movement.

The attack began in the center, where the Uruguayans were forced back by surprise with some Brazilian Volunteer Battalions. On the left of the allied encampment, Captain Emilio Mallet had ordered the construction of a large moat in front of his artillery pieces. When the Paraguayan onslaught reached it, they were in grapeshot range and unable to cross the obstacle. The Paraguayans tried to circle the artillery, avoiding the incoming fire, but encountered Antonio Sampaio's 3rd Infantry Division. This unit fought desperately in the muddy terrain with its commander dying in the process, having fought stubbornly. At this point, Osório ordered his reserves to attack and repelled the Paraguayan center.

On the allied left, the Paraguayans forced back the few Brazilian units, almost reaching the Allied camp. Osório reinforced the Brazilian lines with various units, finally committing the 2nd Cavalry Division, commanded by General Mena Barreto. The Paraguayans continued to attack until they were encircled and annihilated. In the Argentine sector, the Paraguayan cavalry routed the dismounted Argentine cavalry that faced them. Soon, the Argentines had to engage all of their units and even then barely held the enemy.

The Paraguayans fled, losing about 12,000 or 13,000 men, while the allies took about 4,000 or 5,500 casualties, mostly wounded. The largest battle ever fought in South America had just ended. Lopéz's flanking maneuver had failed, but it had been very close to succeeding. In fact, the Allies were unable to pursue the enemy due to the few horses they had remaining. They needed to regain strength and rebuild.