Argentine War of Independence The Argentine War of Independence was fought from 1810 to 1818 by Argentine patriotic forces under Manuel Belgrano , Juan José Castelli and José de San Martín against royalist forces loyal to the Spanish crown . On July 9 , 1816 , an assembly met in San Miguel de Tucumán , declared full independence with provisions for a national constitution . Background . The territory of modern Argentina was part of the Spanish Viceroyalty of the Río de la Plata , with the same capital city in Buenos Aires , seat of government of the Spanish viceroy . Modern Uruguay , Paraguay and Bolivia were part of it as well , and began their push for autonomy during the conflict , becoming independent countries afterwards . The vast area of the territory and slow communications led most populated areas to become isolated from each other . The wealthiest regions of the viceroyalty were in Upper Peru , ( modern - day Bolivia ) . Salta and Córdoba had closer ties with Upper Peru than with Buenos Aires . Similarly , Mendoza in the west had closer ties with the Captaincy General of Chile , although the Andes mountain range was a natural barrier . Buenos Aires and Montevideo , who had a local rivalry , located in the La Plata Basin , had naval communications allowing them to be more in contact with European ideas and economic advances than the inland populations . Also , Paraguay was isolated from all other regions . In the political structure most authoritative positions were filled by people designated by the Spanish monarchy , most of them Spanish people from Europe , without strong compromises for American problems or interests . This created a growing rivalry between the Criollos , people born in America , and the peninsulares , people arrived from Europe ( the term " Criollo " is usually translated to English as " Creole " , despite being unrelated to most other Creole peoples ) . Despite the fact that all of them were considered Spanish , and that there was no legal distinction between Criollos and Peninsulares , most Criollos thought that Peninsulares had undue weight in political conflicts and expected a higher intervention in them . The ideas of the America n and French Revolution s , and the Age of Enlightenment , promoted desires of social change within the criollos . The full prohibition imposed by Spain to trade with other nations was seen , as well as a cause of damage to the viceroyalty ' s economy . The population of Buenos Aires was highly militarized during the British invasions of the Río de la Plata , part of the Anglo - Spanish War . Buenos Aires was captured in 1806 , and then liberated by Santiago de Liniers with forces from Montevideo . Fearing a counter - attack , all the population of Buenos Aires capable to bear arms was arranged in military bodies , including slaves . A new British attack in 1807 captured Montevideo , but was defeated in Buenos Aires , and forced to leave the viceroyalty . The viceroy Rafael de Sobremonte was successfully deposed by the criollos during the conflict , and the Regiment of Patricians became a highly influential force in local politics , even after the end of the British threat . The transfer of the Portuguese Court to Brazil generated military concern . It was feared that the British would launch a third attack , this time allied with Portugal . However , no military conflict took place , as when the Peninsular War started Britain and Portugal became allies of Spain against France . When the Spanish king Ferdinand VII was captured , his sister Carlota Joaquina sought to rule in the Americas as regent , but nothing came out of it because of the lack of support from both the Spanish Americans and the British . Javier de Elío created a Junta in Montevideo and Martín de Álzaga sought to make a similar move organizing a mutiny in Buenos Aires , but the local military forces intervened and thwarted it . Spain appointed a new viceroy , Baltasar Hidalgo de Cisneros , and Liniers handed the government to him without resistance , despite the proposals of the military to reject him . May Revolution . The military conflict in Spain worsened by 1810 . The city of Seville had been invaded by French armies , which were already dominating most of the Iberian Peninsula . The Junta of Seville was disestablished , and several members fled to Cádiz , the last portion of Spain still resisting . They established a Council of Regency , with political tendencies closer to absolutism than the former Junta . This began the May Revolution in Buenos Aires , as soon as the news were known . Several citizens thought that Cisneros , appointed by the disestablished Junta , did not have the right to rule anymore , and requested the convening of an open cabildo to discuss the fate of the local government . The military gave their support to the request , forcing Cisneros to accept . The discussion ruled the removal of viceroy Cisneros and his replacement with a government junta , but the cabildo attempted to keep Cisneros in power by appointing him president of such junta . Further demonstrations ensued , and the Junta was forced to resign immediately . It was replaced by a new one , the Primera Junta . Buenos Aires requested the other cities in the viceroyalty to acknowledge the new Junta and send deputies . The precise purpose of these deputies , join the Junta or create a congress , was unclear at the time and generated political disputes later . The Junta was initially resisted by all the main locations around Buenos Aires : Córdoba , Montevideo , Paraguay and the Upper Peru . Santiago de Liniers came out of his retirement in Córdoba and organized an army to capture Buenos Aires , Montevideo had naval supremacy over the city , and Vicente Nieto organized the actions at the Upper Peru . Nieto proposed to José Fernando de Abascal y Sousa , viceroy of the Viceroyalty of Peru at the North , to annex the Upper Peru to it . He thought that the revolution could be easily contained in Buenos Aires , before launching a definitive attack . Buenos Aires was declared a rogue city by the Council of Regency , which appointed Montevideo as capital of the viceroyalty of the Río de la Plata , and Francisco Javier de Elío the new viceroy . However , the May Revolution was not initially separatist . Patriots supported the legitimacy of the Juntas in the Americas , whether royalists supported instead the Council of Regency ; both ones acted on behalf of Ferdinand VII . All of them believed that , according to the retroversion of the sovereignty to the people , in the absence of the rightful king sovereignty returned to the people , which would be capable to appoint their own leaders . They did not agree on who was that people , and which territorial extension had the sovereignty . Royalists thought that it applied to the people on European Spain , who had the right to rule over all the Spanish empire . The leaders of the May Revolution thought that it applied to all the capitals of Spanish kingdoms . José Gervasio Artigas would lead later a third perspective : the retroversion applied to all regions , which should remain united under a confederative system . The three groups battled each others , but the disputes about the national organization of Argentina ( either centralist or confederal ) continued in Argentine Civil War , for many years after the end of the war of independence . Armed conflict . The Primera Junta sent military campaigns to the viceroyalty , in order to secure support to the new authorities and retain the authority held as the capital of the viceroyalty . The victories and defeats of the military conflict delimited the areas of influence of the United Provinces of the Río de la Plata , the new name given by Buenos Aires to the former viceroyalty . With the non - aggression pact arranged with Paraguay early on , most of the initial conflict took place at the Upper Peru at the north and the Banda Oriental at the east . On the second half of the decade , with the capture of Montevideo and the stalemate in the Upper Peru , the conflict moved to Chile , to the west . First Upper Peru campaign . One of the first two military campaigns sent from Buenos Aires moved to Córdoba . Santiago de Liniers organized a counter - revolution , but there was no battle : all the army deserted before it . Liniers attempted to move to the north and join Nieto and Goyeneche , but Francisco Ortiz de Ocampo captured him and the other leaders of the counter - revolution . Instead of executing them as instructed , he sent them to Buenos Aires as prisoners . He was demoted as a result , and Juan José Castelli appointed head of the military campaign instead . Castelli executed the prisoners , and the army headed then to the Upper Peru . Antonio González Balcarce moved ahead , and was defeated at the battle of Cotagaita . Castelli sent him reinforcements , and got the first victory at the battle of Suipacha , which gave control of the Upper Peru . The royalist generals Vicente Nieto , Francisco de Paula Sanz and José de Córdoba y Rojas were captured and executed . Castelli proposed to the Junta to cross the Desaguadero River and expand the military conflict to the Viceroyalty of Peru , but his proposal was rejected . His army and Goyeneche ' s stationed near the frontier , while negotiating . Goyeneche advanced and defeated Castelli at the Battle of Huaqui , whose forces dispersed and left the provinces . The resistance of Cochabamba kept the royalists at the Upper Peru , preventing them from advancing to Buenos Aires . Castelli returned to the city and died of cancer during a lengthy trial of his actions . Other trialed officers would be pardoned later . Paraguay campaign . Paraguay campaign ( 1810 – 1811 ) : Another militia , commanded by Manuel Belgrano , made its way up the Paraná towards the Intendency of Paraguay . A first battle was fought at Campichuelo , where the Argentines claimed victory . However , they were completely overwhelmed at the subsequent battles of Paraguarí and Tacuarí . Thus , this campaign ended in failure as well from a military point of view ; however , some months later , inspired on the Argentine example , Paraguay broke its links with the Spanish crown and became an independent nation . Violent internal disagreements and the undesired outcomes of these campaigns , led to the replacement of the Junta for a triumvirate in September 1811 . The new government decided to promote another campaign to the Upper Peru with a reorganized Army of the North . Second Upper Peru campaign . Second Alto Perú campaign ( 1812 – 1813 ) : Facing the overwhelming invasion of a royalist army led by General Pío de Tristán , Manuel Belgrano , then commander of the Northern Army , turned to scorched - earth tactics . He ordered the evacuation of the people and the burning of anything else left behind , to prevent enemy forces from getting supplies or taking prisoners from the city of San Salvador de Jujuy . This action is commonly known as the Jujuy Exodus . General Belgrano led the Northern Army to victory in the Battles of Tucumán and Salta , in the northwest of present - day Argentina , forcing the bulk of the royalist army to surrender their weapons . Tristán ( a former fellow student with Belgrano at Salamanca University ) and his men were granted amnesty and released . The cities of Tucumán and Salta have remained under the Argentine government ever since . But , then again the patriot army was defeated into the Upper Peru at the battles of Vilcapugio and Ayohuma . Campaigns of José de San Martín . Meanwhile , the Triumvirate named a recently arrived from Spain José de San Martín Lieutenant Colonel , and ordered him to create the professional and disciplined cavalry unit Regiment of Mounted Grenadiers ( ) . By late 1812 , this same division helped a revolution that deposed the government and promoted the creation of a new Trimuvirate On January 31 , 1813 , a Spanish army company coming from Montevideo landed near the town of San Lorenzo , Santa Fe Province . The Second Triumvirate urged San Martín to stop further raids on the west bank of the Parana river . The " Granaderos " division met the Spanish on a field near the town ' s convent and made it an easy victory on February 3 . After the Battle of San Lorenzo , the Triumvirate awarded San Martín the rank of General . Fearing a major Spanish attack , a general assembly known as " Asamblea del Año XIII " was summoned in Buenos Aires on February 27 , 1813 , to discuss future military campaigns and with provisions for a Constitution . It was decided there to dissolve the Triumvirate and to create a new unipersonal office for an effective executive action . The assembly elected Gervasio Antonio de Posadas as the first Supreme Director on January 31 , 1814 . Posadas decided to create a naval fleet with the funding of Juan Larrea , and appointed William Brown as Lieutenant Colonel and Chief Commander of it , on March 1 , 1814 . This tiny fleet engaged in combat with the Spanish ships off the Montevideo coast , this action known as the Action of 14 May 1814 , and defeated the Spanish three days later . This action secured the coasts of Buenos Aires and allowed the subsequent fall of Montevideo , executed by Carlos María de Alvear . All of this meant the end of the royalist menace from the Eastern Bank of the Uruguay river . William Brown was awarded the rank of Admiral and Carlos María de Alvear succeeded his uncle Posadas as the Supreme Director , on January 11 , 1815 . However , he was resisted by the troops , so he was quickly replaced , on April 21 , by Ignacio Álvarez Thomas . Álvarez Thomas appointed Alvear as General of the Northern Army , in replacement of José Rondeau , but the officiality would not recognize this and instead remained loyal to Rondeau . By 1815 , King Ferdinand VII was restored in his throne , so an urgent decision was needed regarding independence . On July 9 , 1816 , an assembly of representatives from all of the Provinces ( except for Santa Fe , Entre Ríos , Corrientes and the Eastern Province , which formed a Federal League ) met at the Congress of Tucumán , and declared the Independence of Argentina from the Spanish Crown with provisions for a national Constitution . Santa Fe , Entre Ríos and Corrientes later joined the United Provinces of the Río de la Plata . The following year , San Martín took command of the Northern Army , to prepare a new invasion of the Upper Peru . However , he quickly resigned as he foresaw yet another defeat . Instead , he developed a new strategy to attack the Viceroyalty of Perú through the Captaincy of Chile , inspired on the writings of Sir Thomas Maitland , who was quoted as saying that the only way to defeat the Spanish at Quito and Lima was attacking Chile first . San Martín asked to became Governor of the Province of Cuyo , where he prepared the Chilean campaign . From here on , the Argentine War of Independence gets mixed with the Chilean War of Independence , as patriots from both countries joined their forces . This is considered to be the conclusion of the Argentine War of Independence , but battles continued by land and sea into Peru until 1824 , when the last decisive battle was fought in Ayacucho . These events were part of San Martín ' s own campaigning with O ' Higgins and Simón Bolívar , and Buenos Aires no longer recognized his authority . The meeting of Guayaquil . On 26 July 1822 , San Martín met with Simón Bolívar at Guayaquil to plan the future of Latin America . Most of the details of this meeting are secret , and this has made the event a matter of much debate among historians . Some believe that Bolívar ' s refusal to share command of the combined forces made San Martín withdraw from Perú and resettle as a farmer in Mendoza , Argentina . Another theory claims that San Martín yielded to Bolívar ' s charisma and avoided a confrontation . It is widely believed that both men were members of Masonic societies , and the outcome of the meeting might have been arranged by hidden players , however this has been denied by the Great Masonic Lodges See Lautaro Lodge . Annual commemoration . The " Día de la Revolución de Mayo " ( May Revolution Day ) on May 25 is an annual holiday in Argentina to commemorate the First National Government ( and the creation of the Primera Junta ) , one of the significant events in the history of Argentina . These and other events of the week leading to this day are referred to as the " Semana de Mayo " ( May Week ) .