[2][4] When he returned to Venezuela in 1827, he studied mathematics and topographical drawing at the Army Engineering Command in Puerto Cabello, and was later stationed in Bogotá and Cartagena.

[2] During this period he participated in the punitive expedition under Daniel Florence O'Leary that went to Antioquia to suppress the revolt of General José María Córdova against the dictatorship of Simón Bolívar.

[2] In 1842, the Venezuelan government appointed a commission to repatriate the remains of Simón Bolívar from Santa Marta, an event that Fernandez recorded with about twenty drawings.

[2][3][4] The prints he made during the project numbered about thirty,[2][4] and are divided thematically into landscapes of natural phenomena, sites of historical and archaeological significance, roads, ethnic groups and customs.

[2] He also decorated the Paéz's home in Valencia as well as designing the "Plaza de Bolívar" in Maracaibo and planning restorative work on Solano Castle in Puerto Cabello.