Son to Colonel José del Carmen Pérez, one of the members of the 1870 constitutional assembly, and Juana Rosa Acosta.

The figure of Father Pérez soon acquired notoriety; his appealing and educated personality, his affable treatment, and firm discipline gave him prestige and popularity.

In 1927 he was appointed director of the Salesian College of the Sacred Heart and, the following year, councilor of the city of Asunción.

Appointed chaplain, he became famous for his participation in the defense of Fort Nanawa, one of the war's main battles, where he fought alongside the soldiers as an infantryman.

He became friends with the overall commander of the fort, Luis Irrazábal, and soon was made head chaplain for the Paraguayan III Corps.