Battle of San Lorenzo The Battle of San Lorenzo was fought on February 3 , 1813 in San Lorenzo , Argentina , then part of the United Provinces of the Río de la Plata . A Spanish Royalist force under the command of Antonio Zabala was defeated by the Regiment of Mounted Grenadiers , under the command of José de San Martín . This battle was the baptism of fire for this military unit , and for San Martín in the Spanish American wars of independence . Montevideo , a royalist stronghold during the Argentine War of Independence , was under siege by José Gervasio Artigas . Those in the city raided population centres along the nearby rivers for supplies . José de San Martín , who shortly before had arrived in Buenos Aires and formed the regiment , followed the royalist ships to San Lorenzo . The area around San Lorenzo formed a large empty plain , so the regiment hid inside the San Carlos convent during the night and San Martín studied the battlefield and the enemy ships from the tower . The battle started at dawn , when the grenadiers made a surprise pincer movement to trap the enemy forces . One column was led by San Martín , and the other by Justo Germán Bermúdez . San Martín fell from his horse , and was nearly killed , but Juan Bautista Cabral and Juan Bautista Baigorria intervened and saved him . The royalists were defeated , but continued to raid villages for some more time afterwards . This battle was the only one that San Martín fought on the modern territory of Argentina . The city of San Lorenzo keeps historic memorials of the battle and it is referenced in the San Lorenzo march . Prelude . Although Buenos Aires had suffered a difficult period in its war for independence , its prospects were improving by 1812 . Even though the defeats of Manuel Belgrano during the Paraguay campaign and Juan José Castelli in the first Upper Peru campaign had generated a political crisis , Belgrano ' s victory at Tucuman had given new fresh hope to the revolution , which would be strengthened shortly afterwards with the victory at the Battle of Salta . Montevideo , capital of the Viceroyalty of the Río de la Plata since the May Revolution , was under siege by both an army from Buenos Aires led by José Rondeau and an Uruguayan one led by José Gervasio Artigas . The city , however , maintained its naval supremacy over Buenos Aires and their ships raided the coasts of the Paraná and Uruguay rivers to gather supplies , despite the siege . Montevideo organized a navy to destroy the gun batteries at Rosario and Diamante , two population centers along the Parana , but were prevented from doing so as Buenos Aires dismantled them knowing that they could not defend them . The Royalist expeditionary navy that would raid San Lorenzo comprised eleven ships of varying sizes , two hundred and fifty soldiers and fifty sailors . They moved into the Paraná through its tributary , the Paraná Guazú River , slowed down by headwinds . The Second Triumvirate promoted José de San Martín to colonel and instructed him to follow them with the Regiment of Mounted Grenadiers and stop the raids . San Martín was influenced by Napoleonic warfare and trained the regiment with the most recent military techniques used in the Napoleonic Wars . San Martín moved the regiment from Retiro to Rosario , nearing the river at San Pedro and San Nicolás . He was following the Spanish ships and moved at night to avoid detection . San Martín had one hundred and twenty men for this action , reinforced at Rosario by a militia of seventy men under the command of Celedonio Escalada . Those reinforcements included twenty two rifleman , thirty cavalry , a small cannon and men armed with knives . Escalada had made other actions against the royalists before this battle . San Martín discovered that the royalists intended to pillage the San Carlos Convent and pressed the march to arrive there first . A hundred royalists landed on San Lorenzo , but the only food available to them was some chickens and watermelons . Aware of the risk of pillage , the population had removed the cattle from the area before the royalists arrived . Escalada arrived in San Lorenzo before the bulk of the patriot army , but the dust trail from the path to Rosario revealed their presence . Escalada attacked them but their ship had a longer range than his cannon , keeping him at bay . He was forced to retire when he found a Paraguayan prisoner who had escaped from the ship . The Paraguayan disclosed the size of the royalist army and their plan of attacking the convent with a larger force , suspecting that the local money was kept in it . They did not attack the convent right away , requiring time to prepare the two field cannons . Escalada returned with San Martin and relayed the news . The march from Retiro to the convent took only five days , thanks to the cadet Ángel Pacheco . Pacheco moved ahead of the regiment and prepared horses in advance at the relay positions . The whole army arrived on scene during the night of 2 February and hid inside the convent . They entered through the rear door and were not allowed to light fires or speak during the night . San Martín studied the enemy and the battlefield from the convent ' s tower , using a monocular . Battlefield . The battle was fought at the location of the modern city of San Lorenzo , Santa Fe which is next to the Paraná River , at the point of its widest flow . The west bank of the river was tall and steep , forming a natural obstacle , and ships could only land troops and materials on that side of the river using man - made paths cut into the side . The battlefield was near one of these paths , shaped like a ladder , after which the terrain was a big plain with scattered bushes . The San Carlos Convent , the main nearby building , was a short distance away from the river . The location was not an easy place to defend without artillery , as the plains made surprise attacks difficult . Except for the convent itself , the terrain did not offer any natural barrier s that the patriots could exploit . Nevertheless , the flat terrain was ideal for cavalry manoeuvres , and the distance between the church and the west gully gave enough room for a cavalry charge . The royalists , on the other hand , could support their troops with their ships from the river . Without a supporting navy , or local batteries , San Martín had no means to attack the ships . Although the small path allowed them passage to the ships , it could force the royalist forces to bottleneck during a retreat while the long range guns of the ships protected them . San Martín studied the battlefield and readied the plan for the operation during the night , when the grenadiers were hidden inside the convent . Battle . The grenadiers left the convent at dawn , preparing their formations behind the convent . San Martín returned to the tower to watch the enemy who disembarked at sunrise , 5 : 30 in the morning . He mounted his horse , gave a short harangue to the troops , and headed to battle . His strategy was to divide his cavalry forces into two columns , of nearly sixty horsemen each , and make a surprise pincer movement to trap the enemy forces . The cavalry would not use their guns , relying instead on saber and spear attacks . The right - hand column was headed by Justo German Bermúdez , and the left - hand one by San Martín . The royalists marched in two columns with the two cannons , a deployed flag and military drummer s . The clarion of the regiment of mounted grenadiers sounded for the first time , marking the beginning of the battle . San Martín ' s column was the first one to reach the enemy . The two cannons and the cannon fire from the ships defended the royalists , but they were quickly outmanoeuvred by the saber attacks and , unable to form a square , had to retreat . The advantage of surprise and the speed of the cavalry charge allowed the regiment to defeat the larger royalist army who had almost double the amount of soldiers . When Bermúdez and his column joined the battle the royalists were not able to stand their ground and were rout ed , retreating in disarray under covering fire from the ships . Bermudez led the attack at this point as San Martín had fallen from his horse . San Martín did not mention Escalada in his first battle report , leading initial historians to infer that they stayed within the convent during the battle . However it is currently considered that they took part in the battle , as suggested by the royalist battle report and a later report from San Martin which clarifies that only twelve grenadiers stayed in the convent . The combat took around fifteen minutes and left forty royalists dead and many injured , including Zabala . Fourteen patriot grenadiers died in the combat and two more would die afterwards due to combat injuries . Manuel Díaz Vélez fell from his horse in the gully , was mortally injured and captured by the royalists . Bermúdez was shot in the patella and died a few days later . Hipólito Bouchard captured the Spanish flag after killing the standard bearer . Cabral ' s intervention . Despite the victory , the remaining royalist forces could not be pursued as the column led by Justo Bermúdez had moved further than calculated for . This delayed the meeting with San Martín ' s column whose horse was killed by enemy fire , leaving with his leg trapped under the corpse of the animal . These factors led to the columns not meeting up and allowed many royalists to escape . A royalist , probably Zabala himself , attempted to kill San Martín while he was trapped under his dead horse where he suffered a saber injury to his face , and a bullet wound to his arm . Juan Bautista Cabral and Juan Bautista Baigorria intervened and saved San Martín ' s life . Cabral was mortally wounded during the rescue and San Martín reported that after Cabral was hit he said " I die happy , we have defeated the enemy " . The exact moment this was said is unclear as the word " after " could have meant immediately after ; during the ongoing battle ; or some hours later during Cabral ' s agonising decline . San Martín wrote the battle report under a nearby tree . Fray Herminio Gaitán considers that Cabral ' s last words would have been in the Guaraní language , his first language , and that as San Martín also spoke Guaraní he would have translated them for the battle report . Juan Bautista Cabral is commonly known as " Sergeant Cabral " , but he was a private at the time of the battle . San Martín ' s report mentions him as " the grenadier Juan B . Cabral " , and historians like Bartolomé Mitre , Herminio Gaitán , Gerardo Bra or Norberto Galasso support the idea . Mitre considers that Cabral was promoted posthumous ly , but there are no documents confirming that . Aftermath . Even though the battle of San Lorenzo is acknowledged in Argentine historiography as an important battle for Argentine independence , it had little military influence in the conflict . Much of the recognition the battle generated is because San Martín fought in it , as the size of the forces involved and the length of the clash would normally mean it was considered a military engagement rather than a real battle and it did not influence the development of the Argentine War of Independence . This victory did nothing to prevent further raids from royalist ships as there were new raids at Tigre on August 18 , 1813 and yet another one at San Fernando on August 22 . William Brown ended the royalist naval supremacy the following year . San Martín did not take hostages or ask for ransoms , but rather he instructed his people to avoid further conflicts and to try to restore peaceful relations with the royalists . Zabala requested assistance for his wounded soldiers , which San Martín provided and he invited Zabala to share a large breakfast , which he accepted . San Martín was aware that the new enlightened ideas at stake in the Napoleonic Wars influenced many of the Spanish military , and expected to convince Zabala that absolutism was a bad cause to defend . He succeeded , as Zabala joined the patriot forces under San Martín ' s command during his administration in Mendoza . José Gervasio Artigas , leader of the popular resistance at the Banda Oriental , sent an agent to San Lorenzo to congratulate San Martín for his victory . San Martín also met with John Parish Robertson , who informed Britain about the battle . Legacy . There are many Argentine memorials and places named after the battle , including four cities in Greater Rosario : Puerto General San Martín , Fray Luis Beltrán , Capitán Bermúdez and Granadero Baigorria are named after José de San Martín , Luis Beltrán , Justo Germán Bermúdez and Juan Bautista Baigorria respectively , all of whom were involved in the battle . The Sargento Cabral Department at the Chaco Province is named after Juan Bautista Cabral , even though he was not a sergeant as described . The most popular homage to the battle is the name of the football club San Lorenzo de Almagro , named after both the battle and Saint Lawrence . The city of San Lorenzo preserves the site of the battle and a dedicated historic complex . The San Carlos Convent is still a working convent , but has turned part of its buildings into a museum . It has retained San Martín ' s cell , the room used for medical treatment of the injured soldiers , urns of the dead soldiers and other related items to the " March of San Lorenzo " as well as the history of the convent . Raimundo , mayor of San Lorenzo , made an agreement with the Argentine Armed Forces in 2008 that the Regiment of Mounted Grenadiers would have a permanent presence at the site . The battlefield is known as the " Field of Glory " , and it was turned into a park on May 20 , 1913 , by president Roque Sáenz Peña . There is a monument with two symbolic wings of victory , an eternal flame and nine memorials for the 16 patriot soldiers who died in the battle . The memorials are for the nine origins of those soldiers : the Argentine provinces of Corrientes , Santiago del Estero , La Rioja , Córdoba , San Luis and Buenos Aires , as well as Chile , France and Uruguay . Although Uruguay did not exist at the time of the battle , the Banda Oriental province is considered a predecessor of modern Uruguay . The pine tree ( Pinus pinea ) where San Martin wrote the battle report is known as the " Historic Pine " , and has an estimated age of more than two hundred years . The convent , the battlefield and the Historic Pine were declared National Historic Monuments of Argentina on October 2 , 1940 by law 12 . 648 . The Historic Pine was declared a " Historic Tree " in 1946 by decree 3 . 038 . Songs . The battle of San Lorenzo is the theme of the San Lorenzo march . The military march was composed in February 1901 by Cayetano Alberto Silva following a proposal from Representative Celestino Pera . It was first officially played on October 30 , 1902 at the inauguration of the monument to General San Martín in Rosario . The lyrics were written by professor Carlos Benielli in 1908 . The march became famous in other countries and , according to the Argentine British Community Council , it has been considered in Europe to be one of the five best military marches ever written . The military bands of Uruguay , Brazil and Poland , amongst others , include it in their musical repertory . The battle of San Lorenzo was also mentioned as an Argentine victory in the first Argentine National Anthem , along with the battles of San José , Suipacha , Las Piedras , Salta and Tucumán . There is also a brief reference to the battle in the march " Mi bandera " ( " My flag " ) , which is about the flag of Argentina . However , this march includes a historic inaccuracy . It says " Here is the flag that one day triumphantly rose in the middle of the battle and , full of pride and gallantry , went immortally to San Lorenzo " . This is incorrect as the current flag of Argentina was not widely used until 1814 or 1815 . The Battle of Salta was the only conflict of the Argentine War of Independence fought in current Argentine territory under the modern flag of Argentina . The San Martín National Institute states , by oral tradition , that the grenadiers of San Lorenzo did not use any flag for the operation .