He sent on this expedition nine steamers, river boats, about all he had. They were the Tacuari (flag-ship), Paraguari, Igurey, Marquis Olinda (captured early in the war), Salto-Oriental, Ipora, Peribebui, Jejui and Ibera. These carried thirty-four guns. They were to tow down some of the “chatas” or flat-boats used by the Paraguayans, which each mounted one heavy gun, and carried a number of men. These boats were very low in the water, of light draught, and very hard to hit.
Pedro Mesa was the Captain of the Paraguayan Navy. He was fat, and sick, and old, and had no knowledge whatever of naval warfare. He tried to decline the command of the expedition, which, as the whole navy was in service, naturally fell to him. But Lopez would not listen to it, and ordered him on board; and the instructions of Lopez must be obeyed, on peril of death.
Finally the flotilla got off. But there was much delay from defective machinery and one of the steamers, the Ibera, had to be left behind. Owing to this it was broad daylight before they came down near the Brazilians, and there was consequently no surprise. Mesa carried out his orders literally, as it behooved any one to do who served Lopez, and ran past the Brazilians a very considerable distance, having received their fire as he passed. The latter slipped their cables and got under way, so that it was ten o’clock in the morning before the fleets came in contact. In spite of the bad manœuvre of going down the stream first, the fight opened well for the Paraguayans. The Jequitinhonha, which carried, among other guns, two 68-pounders and a Whitworth rifle, grounded, and was abandoned, after being well peppered by the Paraguayan battery of Bruguez, on the left bank. The Paranahyba had her wheel shot away, and was boarded and taken; and the Belmonte, riddled with shot, had to be run on shore, to keep her from sinking.
In this battle the difficulty was for the Paraguayans to hold on to the Brazilian vessels after they got alongside them, for the latter, being screws, managed to slide away from them. Strange to say, grappling irons had been forgotten.
Colonel Thompson says that whenever the Paraguayans boarded, a portion of the Brazilian crew would jump overboard, some of whom were drowned, and some swam ashore, all the latter being killed as soon as they landed.
Burton remarks that the failure to bring grappling irons on an expedition where boarding the enemy was to be a feature, reminded him of an English attack upon some Sikh batteries, where the English engineers forgot to bring spikes.
The Paraguayan launches, which had been towed down below the Brazilians, got adrift, and as they could not get up again, against the current, were eventually captured.
At the end of the first period of the action the Brazilians had lost three vessels in a very few minutes, and their case seemed very doubtful.
Just then a man of ability came to the front, and saved the day. The chief pilot of the Brazilian fleet was the son of an Italian emigrant, named Gastavino. This man, seeing that the Brazilian commanding officers had entirely lost their self possession, and were doing nothing, and giving no orders, took matters into his own hands. He drove the Amazonas at the Paraguayan flag-ship, cleared her deck with grape, and ran her down. Next he finished the Salto and Olinda, in the same manner; the Amazonas being so high out of water that the Paraguayans could not board her as she came in contact with them. He wound up by sinking the Jejui with his guns. The Marquis Olinda had previously had a shot in her boilers, and almost all her crew were either scalded, or killed or wounded by grape. The other Paraguayan vessels, Tacuari, Igurey and Salto, also suffered in their boilers, and had nearly all their crews killed or wounded.
During the height of the engagement, the Brazilian Paranahyba and the Paraguayan Tacuari fouled. The Paraguayans boarded, sword in hand; at sight of them, most of the crew of the Paranahyba jumped overboard. Her decks were filled with the desperate Paraguayans, and the other Brazilian vessels were afraid to use their guns upon her, for fear of injuring the few of their people who were bravely resisting. These few brave men made so good a resistance that the Paraguayan commander, Mésa, became alarmed for his own safety, and endeavored to retire to his cabin. In so doing he was mortally wounded by a musket ball. The next officer in command to Mésa was hopelessly drunk, and the Brazilians succeeded in backing the Paranahyba away, and she escaped, after much slaughter.