The German monarch's struggle with the papacy…

Saraiva had presented an ultimatum to the Uruguayan government on August 4, stating that there will be a formal declaration of war if it does not accede.

The Uruguayan government has refused to accept the ultimatum, and on August 10, Saraiva had informed Aguirre that the Brazilian commanders will receive orders to begin retaliation.

The following day, Saraiva had delivered to the Vice Admiral Joaquim Marques Lisboa (the Baron of Tamandaré and commander of the Brazilian naval forces in Uruguay) the orders to initiate war operations.

Tamandaré has under his command twelve steamships: the frigate Amazonas; corvettes Niterói, Belmonte, Beberibe, Parnaíba, Jequitinhonha and Recife; and gunboats Mearim, Araguaia, Ivaí, Itajaí and Maracanã.

The Brazilian admiral creates a naval division to patrol the Uruguay River under the command of Francisco Pereira Pinto (later Baron of Ivinhema) that consists of the ships Jequitinhonha, Araguaia and Belmonte.

On August 25, the officer Pereira Pinto sights the Uruguayan steamship Vila del Salto and, despite the warning shots to surrender, it manages to escape to Argentina after a desperate flight from the Brazilian warships.

The first battle of the war will result n the breaking off of diplomatic relations by the Uruguayan government on August 30.

López subsequently breaks diplomatic relations with Brazil—on August 30, 1864—and declares that the occupation of Uruguay by Brazilian troops would be an attack on the equilibrium of the Río de la Plata region.

Uruguay requests Paraguay to intervene in September 1864, after Brazil has begun supporting the rising revolution in Uruguay by Venancio Flores against the Blanco party government of Atanasio Aguirre, who is an ally of Paraguay, which does not have friendly relations with Brazil.

Diplomatically, López wants to ally himself with Uruguay's ruling Blanco Party.

The Colorado party is connected to Brazil and Argentin López accurately assesses the Brazilian intervention in Uruguay as a slight to the region's lesser powers.

He is also correct in his assumption that neither Brazil nor Argentina pay much attention to Paraguay's interests when they formulate their policies.

He is clear that preserving Uruguayan "independence" is crucial to Paraguay's future as a nation.

Having built his army into one of the largest in the Southern Hemisphere, López uses it to play power broker in the Rio de la Plata region.

Consistent with his plans to start a Paraguayan "third force" between Argentina and Brazil, López commits the nation to Uruguay's aid.

López manifests this support via a letter to Brazil, in which he says that any occupation of Uruguayan lands by Brazil will be considered as an attack on Paraguay.

Pereira Pinto meets once again with the Vila del Salto while sailing from Salto to Paysandú on September 7.

The corvettes Belmonte and Jequitinhonha attack it as it tries to escape next to Argentine shore.

The combat only ends when the Uruguayan ship runs aground next to the city of Paysandú, where its crew sets it on fire to prevent it from falling into Brazilian hands.

Tamandaré turns the alliance with Flores into a formality on October 20 in Santa Lucia, establishing cooperation between the Brazilian forces and Uruguayan rebels.

The Uruguayan Blancos, when attacked by Brazil, had asked for help from Paraguay, but López has not directly come to his ally's aid.

Instead, on November 12, 1864, the Paraguayan ship Tacuarí captures the Brazilian merchant steamer Marquês de Olinda, which had sailed up the Río Paraguay to the province of Mato Grosso.

Impounding the Marqués de Olinda in the harbor of Asunción, López imprisons the Brazilian governor of the province of Mato Grosso, who had been on board.

The Brazilian ships blockade of the cities of Paysandú and ...

...Salto.

After four days of siege, Colonel José Palomeque, commander of the Uruguayan troops in Salto, surrenders on the afternoon of November 28.

Paraguay declares war on Brazil on December 13, 1864.

Admiral Tamandaré personally commands the Brazilian naval forces in the blockade of Paysandú that begins on December 3, 1864 with one corvette and four gunboats.

The city is garrisoned by twelve hundred and seventy-four men with fifteen cannons under the command of Colonel Leandro Gómez.

Flores besieges it by land with eight hundred infantrymen and seven cannons and receives on December 4 the support of five hundred and sixty Brazilian troops.

Tamandaré sends a message to Gómez to surrender and avoid unnecessary bloodshed.

The Brazilian envoy, however, is repelled by shots fired under the order of Gómez.

Despite several attacks, the Brazilian and Colorado forces are incapable of taking the city.

Tamandaré opts to wait for the Brazilian army that had entered Uruguayan territory in December 1.

Aguirre sends the Argentine general Juan Sáa with two thousand men to help the besieged forces, forcing the Brazilians to briefly lift the siege and depart to face the new threat.

Sáa, giving up his objective, retreats to the other side of the Rio Negro.

The Brazilian army that had invaded Uruguay with six thousand men and twelve cannons is commanded by Field Marshal João Propício Mena Barreto, the Baron of São Gabriel.

It is followed by twelve hundred militia cavalrymen at the service of the tatter Antônio de Sousa Neto.

On December 29, Mena Barreto camps next to Paysandú with two infantry brigades and an artillery regiment, raising the Brazilian forces to twentt-two hundred and ten men.

The cavalry commanded by Brigadier General Manuel Luis Osório (later Marquis of Erval) remains some kilometers away to protect the besiegers from any unsuspected attack.

Gómez executes a young Brazilian sailor who had been taken prisoner and puts his head in a pole, infuriating the Brazilian troops.

On December 31, the Brazilians and Colorados renew the assault.