The joint force of the Imperial (Brazilian),…

The joint force of the Imperial (Brazilian), Argentine and Uruguayan armies attack Paraguayan fortified trenches on Curupayty on the morning of September 22, 1866.

The Paraguayans are led by General José E. Díaz.

This position is held by five thousand men and forty-nine cannons, some of them in hidden places out of the attackers view.

The Brazilian Navy gives support to the twenty thousand assailants, but the ships have to keep some distance from the guns at the fortress of Humaitá, which leads to the lack of accuracy and impact of the ship's fire.

The Brazilian Navy failure is crucial at the later ground battle result.

The Paraguayans are also successful in misleading their foes: a trench draws most of the Brazilian fire, but the Paraguayan troops ware located elsewhere.

Around twenty percent of the almost twenty thousand allied (Brazilian and Argentine) troops involved in the attack are lost; Paraguay loses less than a hundred men.

The utter failure results in the change of the allied command.

Paraguay's biggest success in the ultimately disastrous Paraguayan War is limited, because its military leader, López, does not counterattack the defeated allies.

Not even a general as celebrated as Díaz will attack without López's orders.

Ultimately, the battle of Curupayty is merely a sideshow and temporary success in what will eventually become a near-extermination of the Paraguayan people.