Treaty of Zaragoza

The Treaty of Zaragoza was a major peace agreement signed on April 22, 1529. It was signed in the city of Zaragoza, located in Aragon. The treaty was between King John III of Portugal and the Habsburg Emperor Charles V. This agreement was necessary to resolve the "Moluccas issue." Both Castile (Spain) and Portugal claimed the Moluccas, also known as the Spice Islands. These islands are located in what is now Indonesia. The islands were extremely valuable because they were the single source of nutmeg and cloves.

The conflict began around 1520 when expeditions from both kingdoms reached the Pacific Ocean. At that time, no agreed meridian of longitude had been established in the far east. Longitude is the measurement of how far east or west a place is located. To prevent early disputes, the two kingdoms had signed the Treaty of Tordesillas in 1494. That treaty created a meridian in the Atlantic Ocean. It gave lands west of the line to Spain and lands east of the line to Portugal. However, the precise location of the line in the far east was unclear. Each side interpreted the maps in the most favorable way for themselves.

Portuguese explorers had already established a presence in the region. Vasco da Gama found a sea route to India in 1498. In 1511, Afonso de Albuquerque conquered Malacca to control Southeast Asian trade. Later, an expedition under António de Abreu reached the islands in 1512. His lieutenant, Francisco Serrão, sailed to Ternate. Serrão built a Portuguese factory and fortress there. His letters to Ferdinand Magellan helped convince the Spanish crown to fund the first circumnavigation of the Earth. Magellan's fleet eventually reached the Moluccas from the east in 1521.

Following the Magellan-Elcano expedition, Spain attempted to colonize the islands. In 1525, Charles V sent an expedition under García Jofre de Loaísa. This fleet included 450 men and seven ships. They reached Tidore and established a Spanish fort. This led to direct conflict with the Portuguese, who were already in Ternate. Skirmishes between the two nations continued for nearly a decade. In 1524, both kingdoms tried to resolve this through the Junta de Badajoz–Elvas. This committee included astronomers, cartographers, pilots, and mathematicians. They wanted to establish an antimeridian to divide the world into two equal hemispheres. However, geographic knowledge was not yet good enough to determine exact longitude. Each side simply used different maps to prove the islands were in their own zone.

Diplomacy eventually moved forward through royal connections. In 1525, Catherine of Austria, the sister of Charles V, married John III of Portugal. In 1526, Charles V married Isabella of Portugal. These marriages strengthened the ties between the two crowns. The Emperor also wanted to avoid expensive conflicts in Asia. He needed to focus his resources on European policy. He specifically needed money to fight the War of the League of Cognac against Francis I of France. This provided a practical reason for the two nations to reach a financial settlement.

The Treaty of Zaragoza established a new eastern border. This line was set at 17 degrees east of the Maluku Islands. This specific placement left the Spice Islands within the Portuguese domain. In exchange for giving up their claim, the King of Portugal paid Emperor Charles V 350,000 gold ducats. The treaty also included a safeguard clause. It stated the deal could be undone if the Emperor chose to revoke it. If that happened, Portugal would be reimbursed the money. However, the Emperor never revoked the treaty because he required the funds for his wars.

The treaty did not create two perfectly equal hemispheres. Because the Tordesillas line was not modified, the two lines divided the Earth into unequal parts. Portugal's portion covered roughly 191 degrees of the Earth's circumference. Spain's portion covered roughly 169 degrees. Under this agreement, Portugal gained control of all lands and seas west of the new line. This included all discovered lands in Asia. Spain was left with most of the Pacific Ocean. Although the Philippines was not mentioned, Spain effectively gave up claims to it because it was west of the line. Later, in 1565, King Philip II successfully established a Spanish trading post in Manila.