Ferdinand Magellan convinces King Charles I to support his voyage to Spice Islands

In October 1517 in Seville, Magellan contacted Juan de Aranda, Factor of the Casa de Contratación. Then, following the arrival of his partner, Rui Faleiro, and with the support of Aranda, they presented their project to the Spanish king, Charles I, future Charles V. Magellan's project was particularly interesting, since it would open the "spice route" without damaging relations with the neighbouring Portuguese. The idea was in tune with the times.

On March 22, 1518 the king named Magellan and Faleiro captains so that they could travel in search of the spice islands in July and raise them to the rank of Commander of the Order of Santiago.

The king granted them:
Monopoly of the discovered route for a period of ten years;

Their appointment as governors of the lands and islands met, with 5% of the resulting net gains.

A fifth of the gains of the travel.

The right to levy one thousand ducats on upcoming trips, paying only 5% on the remainder.

Granting of an island for each one, apart from the six richest, from which they would receive a fifteenth.

The expedition was funded largely by the Spanish Crown and provided with five ships carrying supplies for two years of travel. Several problems arose during the preparation of the trip, including the lack of money, the king of Portugal trying to stop them, Magellan and other Portuguese incurring in suspicion from the Spanish and the difficult nature of Faleiro. Finally, thanks to the tenacity of Magellan, the expedition become ready. Through the bishop Juan Rodríguez de Fonseca they got the participation of merchant Christopher de Haro, who provided some funds and goods to barter.

Around this same time, the Spanish were engaged in trying to find a new route to the Spice Islands (the East Indies, in present-day Indonesia) after the Treaty of Tordesillas divided the world in half in 1494. The dividing line for this treaty went through the Atlantic Ocean and Spain got the lands west of the line, including the Americas. Brazil however, went to Portugal as did everything east of the line, including India and the eastern half of Africa.
Similar to his predecessor Columbus, Magellan believed that the Spice Islands could be reached by sailing west through the New World. He proposed this idea to Manuel I, the Portuguese king, but was rejected. Looking for support Magellan moved on to share his plan with the Spanish king.

On March 22, 1518, Charles I was persuaded by Magellan and granted him a large sum of money to find a route to the Spice Islands by sailing west, thereby giving Spain control of the area, since it would in effect be "west" of the dividing line through the Atlantic. Using these generous funds, Magellan set sail going west toward the Spice Islands in September 1519 with five ships (the Conception, the San Antonio, the Santiago, the Trinidad, and the Victoria) and 270 men.

Magellan moved to Spain, married Diego Barbosa's daughter, and became a Spanish citizen. He then went to the king of Spain, Charles I. He presented a plan that he felt could not fail. He said that he knew of a secret strait through the new continent. He would sail through that strait and go to the Spice Islands. If for some reason he was unable to find the strait, he would turn back and sail the usual way around Africa. The king could not disagree with a plan that meant that one way or another, Magellan would get to the Spice Islands.