John III of Portugal - International Relations

International Relations

The reign of John III was marked by active diplomacy. With Spain, he made alliances through marriage (himself with Catherine of Spain; Isabella, princess of Portugal with Charles V; Maria, princess of Portugal – his daughter – with Philip II of Spain, and others) that ensured peace in the Iberian Peninsula for a number of years. However, the intermarriage of these closely related royal families may have been one of the factors contributing to the poor health of John's children and of future King Sebastian.

John III remained neutral during the war between France and Spain, but stood firm in fighting French corsair attacks. He strengthened relations with the Papal States by introducing the Inquisition in Portugal and the adhesion of the Portuguese clergy to the Counter-Reformation. This relationship with the Catholic Church made it possible for John to name whomever he wanted to important religious positions in Portugal: his brothers Henry and Afonso were made Cardinals, and his natural son Duarte was made Archbishop of Braga.

Commercial relations were intensified with England, the countries of the Baltic regions and Flanders during John III's reign. Meanwhile, at the other end of the world, Portugal was the first European nation to make contact with Japan. In China, Macau was offered to the Portuguese, and soon Portugal controlled major trade routes in the area. In the South, the Portuguese continued its hostile stance against their Muslim rivals and insurgent Indian leaders. John III achieved an important political victory in securing the control of the Maluku Islands, the "Spice Islands" claimed by Spain since the Magellan-Elcano circumnavigation.

After almost a decade of skirmishes in Southeast Asia, he signed the Treaty of Zaragoza with Emperor Charles V on 22 April 1529. It defined the areas of Spanish and Portuguese influence in Asia and established the anti-meridian to the Treaty of Tordesillas.