While the others were distracted, Magellan entrusted a seaman with a perilous assignment. Under cover of darkness, he was to sneak on board Quesada’s ship, Concepción, where he would loosen or sever the anchor cable so that she would slip her mooring. Magellan calculated that the strong nocturnal ebb tide would draw her toward the blockade guarding the mouth of the harbor, giving him just the pretext he needed for launching a surprise attack.
