During the XVI and XVII centuries, Portugal and Spain disputed the hegemony in South America. In 1680, the Portuguese founded Colônia do Sacramento, at Rio Prata (Silver River) Delta, strategic location for gold, silver and cattle commerce.
The Spanish considered the fact an invasion of the Tordesilhas Treat (which stipulated a division of the New Land between Portugal and Spain). The reaction was to take back Colônia, only to be returned in 1683. However the battles continued over the next years forcing Portugal to establish a military settlement in the region.
Santa Catarina Island was chosen for 2 reasons: its strategic position and protected bays which served as good ports. In 1739, José de Silva Paes, was designated to build a defensive system. The first step was to create a defensive triangle fortification in the Northern bay. Then were built São José da Ponta Grossa fort, Santa Cruz de Anhatomirin fort and Santo Antônio de Ratones fort.
Silva Paes also promoted the immigration of people from Azorean Islands in 1748. In the end were built 11 forts in total. However in 23 February of 1777 a navy of 100 ships with 12000 men, commanded by Spanish Dom Pedro Cevallos took the island without resistance.
The island was returned a year later with the Santo Idelfonso Treat.
Since then, the defensive system lost its credibility and was abandoned. Recently restored in 1989 as an initiative of the estate government and local institutions, the forts became a popular tourist attraction.