[1] He was born in Sevilla, Spain,[2] the son of Bartolomé Ortiz de Rozas García de Villasuso and María Antonia Rodillo de Brizuela, belonging to a noble family from Santander.

He began his military career as a cadet in the "Guardias de Corps", a special infantry corps created to serve as custodians of the Spanish monarchs.

[3] In 1742 he was sent to serve in Buenos Aires by order issued in Madrid by Ferdinand VI.

[4] He arrived at the port of Buenos Aires, accompanying to his uncle the future Governor of the Río de la Plata Don Domingo Ortiz de Rozas y García de Villasuso.

His grandson was the caudillo Juan Manuel de Rosas, the main political leader of Argentina towards the first half of the 19th century.