The raids and attacks of the Reconquista in the Iberian Peninsula created captives on both sides who were either ransomed or sold as slaves. The Portuguese crown extended this practice to North Africa. After the attack on Ceuta, the king sought papal recognition of the military action as a Crusade. Such a ruling would have enabled those captured to be legitimately sold as slaves. In response to John's request, Pope Martin V issued the Papal bull "Sane charissimus" of 4 April 1418, which confirmed to the king all of the lands he might win from the Moors. Under the auspices of Prince Henry the Navigator, voyages were organized to explore the African coast. These led to the discovery of the uninhabited islands of Madeira in 1417 and the Azores in 1427; all were claimed by the Portuguese crown.