Lavalle was born in Buenos Aires to María Mercedes González Bordallo and Manuel José Lavalle, general accountant of rents and tobacco for the Viceroyalty of the Río de la Plata.
 In 1799, the family moved to Santiago de Chile, but returned to Buenos Aires in 1807.

In 1812 Lavalle joined the Regiment of mounted grenadiers as a cadet.
 By 1813 he reached the grade of lieutenant and moved to the army, which under orders of Carlos María de Alvear besieged Montevideo.
Lavalle fought against José Gervasio Artigas in 1815 and in the Battle of Guayabos under the command of Manuel Dorrego.
In 1816 Lavalle moved to Mendoza to join the Army of the Andes of the "liberator" José de San Martín and fought in Chacabuco and the Maipú in Chile.
He continued along with San Martín on his way to Peru and Ecuador and took part in the battles of Pichincha and the Riobamba, after which he became known as the Hero of Riobamba.

Because of disagreements with Simón Bolívar, Lavalle returned to Buenos Aires by the end of 1823.
He would later govern Mendoza Province for a short time.
He then fought in the war against Brazil in command of 1,200 cavalry, with great episodes of valour in the battles of Bacacay and Ituzaingó in February 1827, beating the forces of General Abreu and being himself proclaimed General on the field of battle itself.

Like many other nineteenth century Argentines prominent in public life, Lavalle was a freemason.

By the time he returned to Buenos Aires, the President of the United Provinces, Unitarian Bernardino Rivadavia, had resigned, and Manuel Dorrego was elected the federal governor of Buenos Aires Province.
Lavalle, a Unitarian himself, led a coup to take the government and executed governor Dorrego without a trial.
His government then started a reign of terror, aiming to destroy the Federal Party, but the resistance in the countryside didn't recede.
In 1829, the demographic growth was negative as there were more deaths than births.
During that time, José de San Martín had returned from Europe.
While he was in Montevideo, Lavalle offered him the government of Argentina as he probably was the only man capable of putting an end to the chaotic situation, because of his authority over leaders on both sides.
But when he learned about the spiraling factionalist violence, San Martín realised that he would have to choose sides as the only actual way to govern, so he refused and returned instead to self-exile in Europe.

The other provinces did not recognize Lavalle as the legitimate governor, and supported the rosista resistance instead.
Lavalle would be defeated a short time later at the Battle of Márquez Bridge by the forces of Juan Manuel de Rosas and Santa Fe governor Estanislao López.
López returned to his province, menaced by Unitarian José María Paz, who had taken power in Córdoba.
Meanwhile, Rosas kept Lavalle under siege and forced him to resign with the Cañuelas pact.
Juan José Viamonte was designated as interim governor, and the legislature that was removed during Lavalle's coup d'état was restored.
This legislature would elect Rosas as the governor.
Lavalle retired to the Banda Oriental.

During the French blockade to the Río de la Plata, Fructuoso Rivera was reluctant to take military actions against Rosas, aware of his strength.
Unitarians, who thought that the whole Argentine Confederation would rise against Rosas at the first chance, urged Lavalle to lead the attack, who requested not to share command with Rivera.
As a result, they led both their own armies.
His imminent attack was backed up by conspiracies in Buenos Aires, which were discovered and aborted by the Mazorca.
Manuel Vicente Maza and his son were among the perpetrators, and were executed as a result.
Pedro Castelli also organized an ill-fated uprising against Rosas, and was executed as well.
Rosas did not wait to be attacked and ordered Pascual Echagüe to cross the Paraná river and take the fight to Uruguay.
The Uruguayan armies split: Rivera returned to defend Montevideo, and Lavalle moved to Entre Ríos Province.
He expected that the local populations
Lavalle was born in Buenos Aires to María Mercedes González Bordallo and Manuel José Lavalle, general accountant of rents and tobacco for the Viceroyalty of the Río de la Plata.  In 1799, the family moved to Santiago de Chile, but returned to Buenos Aires in 1807. 
In 1812 Lavalle joined the Regiment of mounted grenadiers as a cadet.  By 1813 he reached the grade of lieutenant and moved to the army, which under orders of Carlos María de Alvear besieged Montevideo. Lavalle fought against José Gervasio Artigas in 1815 and in the Battle of Guayabos under the command of Manuel Dorrego. In 1816 Lavalle moved to Mendoza to join the Army of the Andes of the "liberator" José de San Martín and fought in Chacabuco and the Maipú in Chile. He continued along with San Martín on his way to Peru and Ecuador and took part in the battles of Pichincha and the Riobamba, after which he became known as the Hero of Riobamba.
Because of disagreements with Simón Bolívar, Lavalle returned to Buenos Aires by the end of 1823. He would later govern Mendoza Province for a short time. He then fought in the war against Brazil in command of 1,200 cavalry, with great episodes of valour in the battles of Bacacay and Ituzaingó in February 1827, beating the forces of General Abreu and being himself proclaimed General on the field of battle itself.
Like many other nineteenth century Argentines prominent in public life, Lavalle was a freemason.
By the time he returned to Buenos Aires, the President of the United Provinces, Unitarian Bernardino Rivadavia, had resigned, and Manuel Dorrego was elected the federal governor of Buenos Aires Province. Lavalle, a Unitarian himself, led a coup to take the government and executed governor Dorrego without a trial. His government then started a reign of terror, aiming to destroy the Federal Party, but the resistance in the countryside didn't recede. In 1829, the demographic growth was negative as there were more deaths than births. During that time, José de San Martín had returned from Europe. While he was in Montevideo, Lavalle offered him the government of Argentina as he probably was the only man capable of putting an end to the chaotic situation, because of his authority over leaders on both sides. But when he learned about the spiraling factionalist violence, San Martín realised that he would have to choose sides as the only actual way to govern, so he refused and returned instead to self-exile in Europe.
The other provinces did not recognize Lavalle as the legitimate governor, and supported the rosista resistance instead. Lavalle would be defeated a short time later at the Battle of Márquez Bridge by the forces of Juan Manuel de Rosas and Santa Fe governor Estanislao López. López returned to his province, menaced by Unitarian José María Paz, who had taken power in Córdoba. Meanwhile, Rosas kept Lavalle under siege and forced him to resign with the Cañuelas pact. Juan José Viamonte was designated as interim governor, and the legislature that was removed during Lavalle's coup d'état was restored. This legislature would elect Rosas as the governor. Lavalle retired to the Banda Oriental.
During the French blockade to the Río de la Plata, Fructuoso Rivera was reluctant to take military actions against Rosas, aware of his strength. Unitarians, who thought that the whole Argentine Confederation would rise against Rosas at the first chance, urged Lavalle to lead the attack, who requested not to share command with Rivera. As a result, they led both their own armies. His imminent attack was backed up by conspiracies in Buenos Aires, which were discovered and aborted by the Mazorca. Manuel Vicente Maza and his son were among the perpetrators, and were executed as a result. Pedro Castelli also organized an ill-fated uprising against Rosas, and was executed as well. Rosas did not wait to be attacked and ordered Pascual Echagüe to cross the Paraná river and take the fight to Uruguay. The Uruguayan armies split: Rivera returned to defend Montevideo, and Lavalle moved to Entre Ríos Province. He expected that the local populations
Juan Lavalle