Mariano Moreno (; September 23, 1778March 4, 1811) was an Argentine lawyer, journalist, and politician. He played a decisive role in the Primera Junta, the first national government of Argentina, created after the May Revolution.

Moreno was born in Buenos Aires in 1778. His father was Manuel Moreno y Argumosa, born in Santander, Spain, who arrived in the city in 1776 and married Ana María del Valle. Mariano was the firstborn of the Moreno family and had thirteen brothers. During his youth he studied Latin, logic, and philosophy at San Carlos Royal College under Mariano Medrano, followed by college studies of law at Chuquisaca. During these studies, he learned the new ideas of the Spanish Enlightenment. He married María Guadalupe Cuenca and returned to Buenos Aires, becoming a prominent lawyer for the Cabildo. Unlike most other criollos, he rejected the Carlotist project and the administration of Santiago de Liniers, joining instead the ill-fated mutiny of Álzaga against him. He worked for the next viceroy, Baltasar Hidalgo de Cisneros. He wrote the economic paper The Representation of the Landowners, which persuaded the viceroy to open trade with Britain.

Although he was not prominently involved in the May Revolution that deposed Cisneros, he was appointed as secretary of war of the new government, the Primera Junta. Along with Juan José Castelli, he promoted harsh policies against the supporters of the former government and the strengthening of the new one. These policies were detailed in a secret document, the Operations plan; some historians dispute its authorship. Moreno organized military campaigns to Paraguay and Upper Peru and ensured the execution of Santiago de Liniers after the defeat of his counter-revolution. He established the first Argentine newspaper, La Gazeta de Buenos Ayres, and translated Jean-Jacques Rousseau's The Social Contract into Spanish.

When the Junta achieved the first military victories, President Cornelio Saavedra opposed Moreno, favoring moderate policies instead. Allied with Gregorio Funes, Saavedra expanded the number of members of the Junta to leave Morenism in a minority. With disputes still going on, Moreno was appointed to a diplomatic mission to Britain but died at sea on the way there. His brother Manuel Moreno alleged that he was poisoned. His supporters were still an influential political party for some years after his death. Historians hold several perspectives about the role and historical significance of Moreno, from hagiography to repudiation. He is considered the precursor of Argentine journalism.

Birth and studies Mariano Moreno was the eldest of 14 children of poor parents, Manuel Moreno y Argumosa (born in Santander, Spain) and Ana María del Valle. He studied at Colegio Grande de San Carlos, but without living in it, as his family could not afford the price.Wiñaski, p. 18 He graduated with an honorary diploma. He met influential people within the literary field, who helped him to continue his studies at the University of Chuquisaca, even when his father could not afford the cost.Luna, p. 31-32

This was the only large university in South America at the time. He studied the books of Montesquieu, Voltaire, Denis Diderot, Jean-Jacques Rousseau, and other European philosophers of the Age of Enlightenment. He studied English and French languages as well, to understand authors from Britain and France. This allowed him to work as a translator, and he spent several years working with Rousseau's The Social Contract. Moreno was convinced that society could be changed by the power of intelligence and reason.Luna, pp. 13, 35

He also studied philosophical texts of the Spanish Enlightenment under the tutelage of the priest Terrazas and aspired to implement the new ideas in his country. He wrote a thesis with strong criticism of the native slavery at the mines of Potosí, influenced by the Spanish jurist Juan de Solorzano Pereira,Luna, pp. 35–36 the foremost publisher of Indian Law, and Victoria Villalva, fiscal of the Audiencia of Charcas and defender of the indigenous cause.Luna, p. 42

He started his professional career between 1803 and 1804, in the office of Augustine Gascón, officiating as labor counselor for Indians. As a result, he confronted powerful people like the mayors of Cochabamba and Chayanta. He left the city after being threatened and returned to Buenos Aires in 1805 with his wife Maria Guadalupe Cuenca and their newborn son.Luna, p. 44 Once in the city, he became a reporter of the hearings of the Royal Audiencia, a local appeallate court. The Buenos Aires Cabildo, the local council, hired him as an advisor as well. He defended Melchor Fernández, aggrieved by Bishop Benito Lue y Riega, in one of his first cases. In another of his early disputes, he backed the Cabildo in denying the appointment as an ensign of the young Bernardino Rivadavia.Lagleyze, p. 11

A British army invaded Buenos Aires in 1806, as part of the British invasions of the Río de la Plata.Wiñaski, p. 11 Although Moreno was not actively involved with the military counter-offensive which forced them to surrender, he expressed his loyalty to the Spanish crown in writing. He wrote a diary that noted all the events, so that, in the future, his countrymen would know the circumstances which occurred in the city that allowed for an invasion to succeed.Luna, pp. 47–49 The British launched a new offensive in 1807, this time capturing Montevideo. They published a bilingual English–Spanish newspaper known as "The Southern Star" or "La estrella del sur" (the newspaper used both names in conjunction). It advocated free trade and promoted Latin American independence from Spain under British protection.

The Royal Audiencia of Buenos Aires banned the newspaper and requested Moreno to write articles refuting those of the publication. Moreno refused because, although he remained loyal to the Spanish crown, he agreed with some of the criticisms made by the newspaper against the Spanish colonial government.Luna, p. 60 Fearing a new attack to Buenos Aires, Moreno left the city with his whole family and relocated in the countryside. His house in Buenos Aires, left unoccupied, was later used to keep prisoner William Carr Beresford, the British commander of the first invasion. Several friends of Moreno helped Beresford to escape and move to Montevideo, but it is unknown if Moreno was aware of the plan.Wiñaski, pp. 12–13

First political activities

Although Mariano Moreno was a criollo, a Spanish citizen born in the Americas, he did not work with the other criollos of Buenos Aires who sought to promote political changes against the privileges of the Spanish-born. Unlike the criollo politicians Manuel Belgrano and Juan José Castelli, he did not support viceroy Liniers or the Carlotist project, which sought the coronation of Carlota of Spain in the Americas. He joined mayor Martín de Álzaga instead, which allowed him to serve as a legal adviser of the Cabildo. In that capacity, he wrote a petition to the King of Spain, so that the Buenos Aires Cabildo was named Protector of the Cabildos of the Viceroyalty of the Río de la Plata. As a result, all petitions from local cabildos to the King or the Viceroy would be channeled through the Cabildo at the capital.

Martín de Álzaga organized a mutiny on January 1, 1809, and Moreno joined it. Álzaga aspired to replace Viceroy Santiago de Liniers with a government Junta, after learning of the capture of the Spanish King Ferdinand VII during the Peninsular War and the creation of the Junta of Seville. If it prevailed, Mariano Moreno would have been part of the new Junta. The mutiny was defeated by the swift reaction of Cornelio Saavedra, in command of the Regiment of Patricians, who dispersed the crowd and persuaded Liniers not to abdicate. It is disputed by historians whenever the mutiny had similar or opposite goals to those of the May Revolution that would take place a year later. The historians who support the latter perspective try to make attempts to excuse or justify Moreno's involvement;Scenna, p. 12 those who support the former consider instead that Moreno was a revolutionary a year before most other Argentines.Scenna, p. 15 Moreno was Álzaga's lawyer in the trial that followed, which was labeled a trial for "independentism". Liniers did not extend the trial to Moreno himself, for reasons unknown.Scenna, p. 23

Liniers was succeeded by Baltasar Hidalgo de Cisneros a few months later, who pardoned the mutineers to reduce political conflicts. Cisneros allowed free trade as well, as instructed by the Junta of Seville, which benefited British merchants; Britain was allied with Spain in the Peninsular War. The agents of the Consulate of Cadiz asserted that this would hurt the local economy, moral values, social usages, religious practices, and the loyalty to Spain and its monarchy. As a result, Cisneros closed trade again, restoring the Spanish monopsony. A group of hacendados (owners of haciendas), who did not feel adequately represented at the Cabildo, asked Moreno to defend them. Moreno wrote The Representation of the Landowners, a report that represented the export interest of the landowners, encouraged free trade and condemned the privileges of the merchants benefited from the monopsony. It is considered the most comprehensive economic report from the time of the viceroyalty. It represented the new European economic ideas and noted that the legal monopsony with Spain did not prevent British goods from being smuggled into Latin America. Several authors have questioned Moreno's authorship of the paper, considering it instead an update of another, previously drafted by Manuel Belgrano, Secretary of the Commerce Consulate of Buenos Aires, written to make a similar request to the former viceroy Liniers.Scenna, p. 30

Primera Junta

Mariano Moreno had several contacts with groups seeking the removal of Cisneros but was not strongly involved with the May Revolution, which considered the fall of the Junta of Seville a reason to depose the viceroy and create a local junta. At the time, Moreno was still loyal to Álzaga. He attended the May 22 open Cabildo, but according to the father of Vicente Fidel López and the father-in-law of Bartolomé Mitre (both direct witness) he stayed silent at one side and did not join the debate.Scenna, pp. 33–34 He voted for Saavedra's proposal: to remove viceroy Cisneros and replace him with a Junta. Manuel Hermenegildo Aguirre, captain of hussars, proposed that the Cabildo take the reins of government, with five men appointed as counselors, Moreno among them. However, nobody else voted for that proposal, and it was the only one that included him.Balmaceda, pp. 22–23 Moreno felt betrayed when the Cabildo twisted the results of the open Cabildo and created a Junta that would be headed by Cisneros. He refused any further contacts with the revolutionaries and stayed home during the remaining events. The definitive members of the Junta came from a popular petition signed on May 25, which was given to the Cabildo. The reasons for Moreno's inclusion in the list are unclear, as with all other members of the Junta. A commonly accepted theory considers it to be a balance between Carlotists and Alzaguists.Scenna, pp. 46–47