As a reward for his great valour shown in the conquest of Ceuta in North Africa in 1415, his father created him Duke of Viseo. In 1416 he established a base for exploration at Sagres in south-west
Portugal, sponsoring several voyages including (1418-1420) that which discovered Madeira. In this way he gradually mapped the West African coast.
In 1437 he led a disastrous military expedition to Tangier. Between 1444 and 1446, thirty to forty vessels left for Africa under Enrique's authority, mainly on voyages of exploration but also in
search of slaves and gold. In 1455 Enrique forbade the kidnapping of negroes and by 1460 his explorers had reached Sierra Leone. He may have lost his military prestige in 1437, but in 1458 he recovered his
reputation with a successful Moroccan campaign.
 

Source: Leo van de Pas