[1] He was baptized on November 25, 1720, in Buenos Aires, son of Francisco López Osornio and María Gamiz de las Cuevas Álvarez Lasarte, a family of Creole origin, born in the city.

[2] In 1736 Clemente López de Osornio enlisted in the provincial militia of cavalry and served in the defense in the fort of Arrecifes against Indians.

And in 1765 he served as Commanding general of militia in Province of Buenos Aires, where he led an expedition to the Salinas Grandes, west of Bahia Blanca, along the way, he made a census of the tribes that roamed the area, and organized five companies of Blandengues of cavalry intended to garrison the southern border against the Indians.

[8] After his wife died, he was remarried in the Buenos Aires Cathedral on February 25, 1766, to María Manuela Rubio Díaz Gamiz.

[12] He was the maternal grandfather of Juan Manuel de Rosas,[13] a distinguished caudillo, who was Governor of Buenos Aires in uninterrupted form from March 7, 1835, to February 3, 1852.