During the eighteenth century Portugal developed a large military construction process in the Ultramarine possessions, in order to compete with the new born colonial trading empires, mainly Great Britain, Netherlands and France. The Portuguese colonial seashores of the Atlantic Ocean (since the middle of the sixteenth century) and of the Indian Ocean (from the end of the first quarter of the seventeenth century) were repeatedly coveted, and the huge Portuguese colony of Brazil was also harassed in the south during the eighteenth century –here due to problems in a diplomatic and military dispute with Spain, related with the global frontiers’ design of the Iberian colonies.
The Treaty of Madrid (1750) had specifically abrogated the Treaty of Tordesillas (1494) between Portugal and Spain, and the limits of Brazil began to be defined on the field. Macapá is situated in the western branch of Amazonas delta, in the singular cross-point of the Equator with Tordesillas Meridian, and the construction of a big fortress began in the year of 1764 under direction of Enrico Antonio Galluzzi, an Italian engineer contracted by Portuguese administration to the Commission of Delimitation, which arrived in Brazil in 1753.
In consequence of the political panorama in Europe after the Seven Years War (1756-1763), a new agreement between Portugal and Spain was negotiated (after the regional conflict in South America), achieved to the Treaty of San Idefonso (1777), which warranted the integration of the Amazonas basin. It was strategic the decision to build, one year before, the huge fortress of Príncipe da Beira, arduously realized in the most interior of the sub-continent, 2000 km from the sea throughout the only possible connection by rivers navigation. Domingos Sambucetti, another Italian engineer, was the designer and conductor of the jobs held on the right bank of Guaporé River, future frontier’s line with Bolivia.
São José de Macapá and Príncipe da Beira are two big fortresses Vauban’ style, built under very similar projects by two Italian engineers (each one dead with malaria in the course of building), with the oservance of the most exigent rules of the treaties of military architecture.