At last the expedition set sail, on 20 September 1519. It r- eached Tenerife, one of the Canary Islands, seven days later. Here there were the first signs of conflict and disagreement between Magellan, as Captain-General of the fleet, and the Spanish captains in charge of indivdual ships. The main cause of the dispute was that Magellan was a true explorer, anxious to discover more about the world, while his captains were interested only finding a new and profitanle t- rade route to the Spice Islands. In addition, because of the rivalry between Portugal and Spain, Magellan and his captains did not trust each other. Matters came to a head when they started arguing about the course they should follow across the Atlantic. One of the c- aptains, Juan de Cartagena, tried to organize a revolt. Mag- ellan had him arrested and put in chains. For the moment he had restored law and order.