Battle of Sarandí The Battle of Sarandí was fought on October 12 of 1825 , in the vicinity of the Arroyo Sarandí in Uruguay , between troops of the Banda Oriental and the Empire of Brazil . It resulted in a decisive victory for the Orientals . Background . The Banda Oriental was occupied by the United Kingdom of Portugal , Brazil and the Algarves in 1820 under the name of Cisplatine Province , and was incorporated as a Brazilian Province in 1822 when Brazil became independent from Portugal . The Orientals resumed their efforts to get rid of foreign occupation , and after the landing of the Thirty - Three Orientals ( April 19 , 1825 ) engaged the Brazilian forces in a series of actions which included the siege of Montevideo ( May 8 , 1825 ) , led by Manuel Oribe and that of Colonia del Sacramento ( August 18 , 1825 ) . The Battle of Rincón ( September 24 , 1825 ) resulted in a victory for the Oriental forces , and represented a major setback for the Brazilian forces besieged at Montevideo , as Brazilian casualties were high , which included about 8 , 000 horses captured by the Orientals . As soon as the news were known , in Montevideo a force of around 1 , 000 Brazilian soldiers under Colonel Bento Manuel Ribeiro , was organized , with intention to a Brazilian army of similar strength that was in the field , led by General Bento Gonçalves da Silva . Juan Antonio Lavalleja was in Durazno with Oriental troops , and after becoming aware of these news , tried to prevent both Brazilian forces joining in a single army ; this action was unsuccessful . With a major effort Lavalleja was able to muster a force of similar strength , and faced the Brazilian army at the tips of the Arroyo Sarandí , in an area located on the present - day Florida Department , on October 12 , 1825 . The battle . On the morning of the 12th , after arriving to the vicinity of Sarandí creek , Lavalleja was informed that that the enemy was a league away . Lavalleja formed his troops in a battle line facing south , occupying the heights overlooking the road to Paso de Polanco del Yí . The forces under Fructuoso Rivera were placed to the left of Lavalleja ’ s , supporting their flank the Sarandí creek ; those lead by Pablo Zufriategui were in the center , while on the right wing were located the troops lead by Manuel Oribe . The reserves were located behind the centre . Meanwhile , the Imperial troops had reached Sarandi del Yí , and believing that Rivera was on the right bank of the Sarandí creek were surprised to see them the other side . After crossing the stream and reaching higher ground , the Brazilians realized that the whole of the Oriental force was formed in the line of battle . Bento Manuel Ribeiro realized the advantage of the Oriental formation , and rather than attacking realigned his forces . The manoeuver of the Brazilian Army put Lavalleja off - balance , forcing him to change his front from the south to the west , but speed with which the maneuver was carried out caused confusion in the line , leaving Zufriategui in the center and Manuel Oribe at the right . At 8 in the morning the action began . The Oriental artillery opened fire began ; and Ribeiro ordered the Brazilian Army to attack . Rivera charged on Bento Gonçalves , while in the center Oribe was suddenly charged by the Imperial forces of Alvaro de Alencastre whose disciplined troops penetrated the front and reached the Oriental reserves ; this manoeuvre could have been fatal to the Oriental forces . Realizing the danger , Lavalleja charged with the reserve forces against the Brazilians and divided their formation in two . The Oriental right wing charged against the Brazilian left wing , which was trying to support the Brazilian centre . As a result , Alencastre ’ s forces were flanked by Rivera ’ s troops and by the Oriental reserves , which were in pursuit of the scattered troops under Gonçalves Bentos . This allowed Oribe to reorgainize its forces and counterattack . The confusion of the Brazilian troops was huge and caused its dispersion , as they suddenly found themselves charged by the Oriental cavalry , who forced the Imperial troops to leave the battlefield and relentlessly pursued the enemy . Aftermath . The Orientals organised the Congress of Florida and requested reunification with the United Provinces of the River Plate . The General Congress which gathered in the city of Buenos Aires approved on October 24 a law that reunited the Banda Oriental to the United Provinces of Rio de la Plata . Regardless , the Brazilian army retained the northeast of the country , allowing it to keep in touch with its metropolis . For this reason , the Orientals took action to regain control of this area , culminating in the in capture of the Fortress of Santa Teresa on 31 December 1825 ; which was located in the Rocha Department , near the present border with Brazil . From then on the Brazilian forces held only the besieged cities of Colonia and Montevideo . Currently the small town close to the battlefield is called Sarandí Grande .