Manduvirá River Expeditions

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The Manduvirá River Expeditions were the last naval operations of the Imperial Brazilian Navy in the Paraguayan War. From January 5 to August 20, 1869, Brazilian ships patrolled the Manduvirá River in hopes of finding and destroying the remaining Paraguayan ships that had taken refuge there. The Brazilian fleet had 18 ships, including battleships, monitors, gunboats and steamers, while Paraguay’s fleet had about 12 steamers. Three dangerous expeditions were launched along a very shallow, winding river that was filled with obstacles set by Paraguayans, such as sunken ships, logs, chains and carts with stones.

First expedition (early January 1869)
- Command and ships: The squadron is led by Baron of Passagem with battleships Bahia and Tamandaré, and monitors, gunboats and steamers following.
- What happens: The Brazilian fleet advances up the narrow Manduvirá, facing trees and sunken obstacles that slow and block the ships. Paraguayans sink ships to block the passage.
- Outcome: The expedition reaches the mouth of the Manduvirá and blocks the river’s exit. Several Paraguayan boats are sunk or captured. By January 9, the ships return to Asunción. The goal to find and destroy the Paraguayan fleet is only partially achieved, but the Brazilian pressure grows.

Second expedition (April 1869)
- Command and ships: Led by Victório José Barbosa de Lomba, with Jerônimo Francisco Gonçalves in charge of the flotilla. Monitors Santa Catarina, Piauí and Ceará lead the advance, with support from steamboats Couto, João das Botas and Jansen Müller.
- What happens: The Brazilians push upriver again, facing heavy resistance. Paraguayan garrisons and fortifications man a strong defense at Passo Guarayo, with about 1,100 soldiers and artillery.
- Key moment: The Brazilian monitors break through a complex blockade of beams, trees, canoes, chains and stones. Ceará leads the bombardment and helps force a passage through the fortifications.
- Outcome: After a fierce five-hour battle, the Paraguayans suffer heavy losses while Brazil has only minor casualties (about one death and a few injuries). The fleet then moves to the mouth of the Manduvirá and returns to Asunción on August 30. This second expedition is praised for courage and success, but some leaders criticize the strategic value of sinking Paraguayan ships that were already blocked.

Third expedition (August 1869)
- Command and ships: A new flotilla includes gunboat Iguatemi and steamboats Tebicuari, Inhaúma, Jejuí and Lindóia. The mission is to halt any Paraguayan crossing and to deal with ships still held in the Iaguí stream.
- What happens: The fleet advances along the river but faces a blocked passage and shallow water. Paraguayan forces guard the rear, and fires are exchanged as the Brazilians try to approach the blocked ships.
- Key action: On August 20, Paraguayan ships that had been interned in the Iaguí stream are set on fire by the Brazilians, while other exchanges continue along the river.
- Outcome: By August 20, the Manduvirá River is cleared and opened for navigation as far as Rosário, providing a logistical link between Brazilian forces and their supply lines. The Paraguayan navy is effectively destroyed, and the river becomes a secure route for the army's movements.

Aftermath
- The Manduvirá expeditions mark the end of the Paraguayan Navy. The Brazilian fleet’s efforts, though challenging in the difficult river conditions, prevent any remaining Paraguayan ships from posing a threat.
- In the 1970s, a museum was established at the site to preserve some ships recovered from Manduvirá, and a small open-air park was created to honor the ships buried in the Iaguí stream.
- The Manduvirá campaigns also contributed to broader war aims, supplying and supporting Brazilian forces as Paraguayan defenses weakened inland around the Cordilleras.