[2][3] Taking advantage of the darkness of the night and the aquatic plants and rafts that descended by the current, a squadron of canoes covered by branches and foliage and tied up two by two, each crewed by 50 Paraguayans armed with machetes, hatchets and boarding swords, went to board Cabral and Lima Barros.

Confused, they only managed to land 14 canoes on Lima Barros and 8 on Cabral, dumping men on their decks who took over the awnings of the warships.

[2][4] A hand-to-hand fight was fought; the ironclads' crews and soldiers locked themselves inside the casemates, resisting with gunfire.

[5] The battle continued until dawn, when the battleships Brasil, Herval, Mariz e Barros and Silvado approached and fired at the Paraguayans, who gave up the attack, losing up to 400 men and 14 canoes.

[2] On the Brazilian side, there were 16 dead, including captain of sea and war Joaquim Rodrigues da Costa and first lieutenant João de Gomensoro Wandenkolk.