Empire of Brazil United Provinces 1 brigantine 11 schooners 5 gunboats 61 total guns 1 brigantine 5 schooners 1 smack 8 gunboats 69 total guns 745-780 men The naval Battle of Juncal took place between a squadron of the newly independent United Provinces of the River Plate under command of William Brown and a squadron belonging to the Brazilian Empire, commanded by Sena Pereira.

The two squadrons were initially of roughly equal strength, but because of superior command and control, and gunnery training, the Argentines scored a decisive victory: out of 17 Brazilian vessels, 12—including the flagship with its admiral—were captured and 3 were burnt.

In the aftermath of the battle, the Third Division, the arm of the Brazilian fleet tasked with controlling the Uruguay River and thus disrupting communications with the Argentine army then operating in the Cisplatina province, was completely destroyed.

During the second year of the Cisplatine War, the Brazilians took advantage of their numerical superiority on sea and divided their naval forces operating in the Río de la Plata sector into three squadrons, or "divisions".

To confront the three threats, each of similar or superior strength to his own forces, the Argentine commander, William Brown, acted rapidly to organize a squadron to advance past the mouth of the Uruguay River, then find and destroy the Third Division.

He landed a small force on the Vizcaino Island to secure it and sent instructions to the militia of Santo Domingo de Soriano to cut supplies to the Brazilian fleet.

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[3] while he finished the preparations, after which he rejoined the fleet by travelling aboard a small whaler.

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.

[citation needed] At noon Brown ordered forward a detachment of six of his gunboats, which could fire at a longer range than his other vessels with their 18-pounder (8.2 kg) guns.

However, the maneuvers of the vessels were disastrous: the goleta Liberdade do Sul grounded, while Dona Januária left the formation and strayed within range of the fire of General Balcarce, Sarandí, and three gunboats.

At 8:00 am, with a southeast breeze, he ordered Sarandí to run up a red flag, the signal for the Argentines to occupy the windward position, marshal into a battle line, and advance towards the Brazilians.

The Argentine fire was effective: a shot from General Balcarce soon destroyed Januária's bowsprit, and another knocked down her foremast, causing such disruption that she was on the point of foundering.

The attack was so rapid and devastating that the captain of Januária, Lieutenant Pedro Antonio Carvalho, ordered his cannon to concentrate on the Argentine artillery while a team remained to attempt to scuttle the ship and he departed with the crew in boats towards the east.

An accurate shot from a heavy Argentine gun knocked down the main mast of Bertioga and the ship, now unable to maneuver, was forced to surrender after a half hour of combat.

Brown retired with four of the prizes towards Martín García to repair damages, write his report, and prepare for the eventual attempt of the Mariath Division, stationed to the south of the island, to force its way north.

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.

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.

[13] On the day following the battle, the schooner Brocoio was pursued and captured, in addition to two gunboats (Paraty and Iguape) that ran aground in the mouth of the Paraná River and were likewise made Argentine prizes.

[14] The dwindling fleet continued north with a total of 351 officers and crew piled aboard, with the intent of surrendering to the authorities of the Province of Entre Ríos.

The next day he arrived at Fray Bentos and received the news that Souza Aranha, after casting his cannon into the sea, had surrendered his ships to the governor of Entre Ríos.

In response to this rebuff Brown mounted a successful combined land and sea operation which resulted in the final capture of the Brazilian fleet.

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.

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".

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".