Belgrano completed his first studies at the San Carlos school. He studied in Spain at the University of Salamanca in 1786 and at Valladolid, where he graduated with a degree in law in 1793.
Belgrano was appointed as captain of the urban militias in 1797 by viceroy Pedro de Melo, who was instructed by Spain to prepare defences against a possible British or Portuguese attack. After 1807 Belgrano became increasingly critical of the Spanish system and found others who agreed with him.
In April he resigned from the Consulado, pleading illness.
But in May, when news reached Buenos Aires that the Spanish junta established in 1808 had been disbanded, Belgrano and his compatriots quickly advocated the creation of a local junta.
On May 25, 1810, when the junta was organized, Belgrano was elected a member.
The initial concern of the junta was defending Buenos Aires while securing the support of the surrounding provincial cities.
In September 1810 the ill-equipped and poorly trained force made an unsuccessful foray into Paraguay.
Belgrano was blamed for the disaster, but after an investigation he was cleared in August 1811.
He was subsequently appointed commander of an army defending the northwestern district from a Spanish invasion from Upper Peru (modern Bolivia).
As a standard for the troops, he designed a banner which later became the national flag.
With the outbreak of hostilities Belgrano was forced to retreat, but at the battle of Tucumán, on September 24, 1812, he disobeyed orders, stood, fought, and checked further Spanish advances.
Buenos Aires was spared, and his disobedience overlooked.
Belgrano followed up the victory with an advance into the northwest.
At Salta, on February 20, 1813, he gained another stunning victory over the royalists, and the way was open for an invasion of Upper Peru.
He returned in February 1816, unsuccessful in obtaining either.
The constant traveling and campaigning exhausted him.
He returned to Buenos Aires in March 1820 and died on June 20.
He held strong religious beliefs, being Roman Catholic.
Manuel Belgrano met María Josefa Ezcurra. Her son, Pedro Pablo, was born on 30 July 1813. Pedro Pablo was adopted by Encarnación Ezcurra and her husband, Juan Manuel de Rosas, who she had married shortly before.
Belgrano also met María Dolores Helguero in Tucumán, and briefly considered getting married. But María Dolores married another man. María Dolores had given birth to his daughter, Manuela Mónica del Sagrado Corazón.
Neither of these children were recognised by Belgrano in his will, where he said he had no children.