[1] As son of Marcos de La Mar y Migura (1736–1794) and his wife Josefa Paula Cortázar y Lavayen (1748–1815), he spent his early childhood in Spain.

He was seriously injured, and although that city finally capitulated, earned the title of "Hero of the Nation" (Benemérito de la Patria en grado heroico) and was promoted to colonel .

After a time, he managed to escape, accompanied by Brigadier Juan María Muñoz y Manito, crossed into Switzerland and then Tyrol and reached the port of Trieste, on the Adriatic Sea, where he sailed back to Spain.

In 1815, Ferdinand VII promoted him to Brigadier, awarded him the Saint Hermenegildo's Cross and appointed him Sub-Inspector of the Viceroyalty of Peru, with the title of Governor of Callao.

During the early days of the Peruvian War of Independence, he remained loyal to the King, and defended the Real Felipe Fortress in Callao, the main port of the Viceroyalty, for the Royalists.

A Royalist relief army, under command of General José Canterac was not able to break the siege or to ship supplies and troops into the fortress, and retreated into the mountains.

[3] With the Royalist troops removed from the former Peruvian viceroyalty, Bolívar created the Government Junta (1825), which was to replace him in his functions for the leadership of the State, while he traveled to Colombia.

He was removed from the Presidency of Peru after less than two years by a coup d'état led by General Agustín Gamarra and died in forced exile in Costa Rica, on 11 October 1830.