Construction and early Fortifications
The history of the Santa Teresa Fortress begins in 1762, when the Portuguese colonel Tomás Luis Osorio, based on the plans of engineer João Gómez de Mello, built an initial defensive structure at the site known as Castillo Chico. It consisted of a trench surrounded by wooden palisades, intended to control the passage of the Angostura.
In 1763, following the offensive led by the Spanish governor Pedro de Cevallos, Spanish forces captured Santa Teresa and San Miguel. Engineer Francisco Rodríguez Cardozo then designed a new, more solid fortification, reinforcing Spanish presence along the frontier.
Between 1765 and 1775, the definitive fortress was constructed under the direction of the French engineer Bartolomé Howel. The fortress was designed as an irregular pentagon with five projecting bastions, reaching a perimeter of 642 meters. This monumental work consolidated Spanish control in the region.
Finally, in 1777, the Treaty of San Ildefonso ratified Spanish possession of Santa Teresa and San Miguel, consolidting their role as key elements of the colonial defensive system in the South Atlantic.