Морское сражение 1827 года в Цисплатинской войне: Победа Брауна у Мартин-Гарсии.

1827 naval battle of the Cisplatine War
Imperial Navy
| combatant2 = United Provinces
Argentine Navy
| commander1 = Sena Pereira
| commander2 = William Brown
| strength1 = 1 brigantine
11 schooners
5 gunboats
61 total guns
750 men
| casualties1 = 12 ships captured 3 burnt casualties unknown
| casualties2 = No ships lost 17 killed in action In response, the Brazilians withdrew further north to Concepción del Uruguay (then still usually called "Arroyo de la China") where they could secure supplies. Worried about the menace that the Mariath Division posed to his rear, Brown decided to fully return to Buenos Aires in search of reinforcements for Martin Garcia Island. He ordered Rosales to return the Sarandí to Uruguay via the Paraná de las Palmas while he finished the preparations, after which he rejoined the fleet by travelling aboard a small whaler.

On 6 January the fortification work was begun. The Mariath Division launched an advance on the island with the corvette Maceió and nine other gunships. On 18 January Brown twice ordered his forces out to meet the Brazilian squadron and both times the Brazilians withdrew after an exchange of cannon fire. Brown wanted on one side to lure the Third Division into combat, yet at the same time he did not want the Mariath Division to join the Third or attack his rear. Helping him navigate the delicate situation was an excellent intelligence network which gave him daily updates on the movement of the Imperial fleet. Essentially, the emissary carrying Rodrigo Pinto Guedes' orders to Sena Pereira had been co opted by Argentine patriots in Montevideo and as a result Brown received timely news of the Imperial fleet's intentions. Thus, he took notice when Pinto Guedes informed Sena Pereira of the orders given to Frederico Mariath to advance towards the south. Brown deduced that the Third Division would descend the river on 7 February in order to link up with Mariath. Brown believed that the fortifications and batteries of Martin Garcia would be ready by then, allowing him to block the Mariath Division while forcing the Third Division into battle. The work at the new fort was duly accelerated; Brown himself worked as a master mason in the hold of Santa Barbara. At the beginning of February there was word that the Third Division was taking on provisions at Arroyo de la China; by the third it had passed Paysandú and on 6 February it approached Higuerita (today's Nueva Palmira) where it arrived the next day. That same day, Brown outlined his plan and assigned each ship a role in the battle. At 10 pm, the vanguard of the Argentine fleet reached the mouth of the Paraná Guazú river and waited for the rest of the fleet to arrive.

The Argentine squadron spent the night of 7 February anchored between Juncal Island and the west bank of the river. At dawn on 8 February the sails of the Brazilians were spotted descending the river, taking advantage of a gentle north wind. Brown gave the order to weigh anchor and placed his ships in a line of battle arrayed obliquely to the southeast from Juncal Island. The goleta Sarandi formed the center of the line, with Maldonando in the vanguard and Balcarce in the rear. The Brazilian fleet continued its advance until the wind died down around 11:30 am, at which point it anchored some from the Argentine line, with the flagship Oriental in the center.

Mariath's orders were to use his ten vessels to overcome the fortifications at Martín García, attack the Argentine rear, and reinforce the Third Division. Although he could already hear cannon fire in the distance, Mariath moved slowly and with great caution. As the main Argentine battery (consisting of nine guns) were on the west side, covering the Grand Canal, Mariath sent a schooner down the Canal del Infierno, the passage to the east of the island, in order to determine if the water was deep enough for his squadron. In response, the garrison moved its mobile battery (consisting of two guns and a Congreve rocket launcher) to the east to defend against a possible landing. The move proved unnecessary, however, as the Brazilian vessel ran hard aground. Mariath was thus dissuaded from taking the eastern route, although his pilot thought it still possible. He commenced an artillery duel with the main batteries, until the storm obliged him to suspend the indecisive action. At this point, Mariath believed that the shallow water, the unpredictable weather, and the formidable batteries at Martín García made passing the island too risky. Thus, on 9 February, while the Third Division was being destroyed, the Mariath Division remained in the distance as a spectator. On 10 February, Mariath finally decided to withdraw in the direction of Colonia de Sacramento, where he arrived a week later. The first news of the defeat reached the Brazilians on the morning of 12 February , when eight survivors of Oriental arrived. Their stories were confirmed by the boat of Lieutenant Carvalho, and later, on 14 February, by the arrival of the only survivors, the schooner Vitoria de Colonia and a gunboat, escorted by the frigate Dona Paula.

With twelve vessels captured, three burnt, and only two survivors, the battle imposed a significant loss on the Brazilians and represented the greatest triumph of the Argentine fleet. In the larger scope of the war, the victory frustrated the Brazilian attempt to cut the lines of communication to the expeditionary force. In addition, it denied the Brazilians use of the Uruguay River to stage an offensive against the Argentine litoral, an offensive which at a minimum could have detached the litoral provinces from the Confederation and at worst may have threatened its existence. In Buenos Aires, Brown was received with bonfires and orchestras. He was elevated to most popular figure of the Republic. Sena Pereira remained a prisoner of Brown, who recognized his valor and commended him to the Argentine government "for his brave and intrepid defense, performed by a soldier". However, Pereira refused to give any pledge and eventually escaped. At the beginning of 1829, he would be one of those who handed over the plaza of Montevideo to the westerners. The republican naval victory off Juncal was rapidly followed on land by Ituzaingó (20 Feb) and Carmen de Patagones (28 February). After this, the conflict ground to a halt, as the Brazilian Empire had been defeated in various fronts while Argentina was incapable of taking advantage of the situation given that the naval blockade still persisted, especially after the Battle of Monte Santiago which almost fully destroyed the navy of the United Provinces of the River Plate, and also given that Montevideo and Colonia, the two largest cities in the Banda Oriental, were still under control by the Empire of Brazil. As the British military historian Brian Vale put it, "to a navy which consisted of 69 warships and 22 packet boat and transport vessels, manned by 10600 officers and men, the loss of [ ] its smallest armed vessels made little difference to the ultimate balance of power". "[ ] Juncal had done little to push the Empire in the direction of peace. Now at Monte Santiago, two of Argentina's precious brigs of war had been destroyed and the cream of its Navy roundly defeated. The Brazilian Navy's overwhelming superiority at sea had been reasserted in a way which neither William Brown's audacity or Ramsay's newly purchased frigates could seriously challenge". This situation would continue until the Preliminary Peace Convention, by which Oriental Province became the independent Eastern State of Uruguay.