1394–1460, prince of Portugal, patron of exploration. Because he fought with extraordinary valor in the Portuguese conquest of Ceuta (1415), he was created duke of Viseu by his father, John I, king of Portugal. The Moroccan campaign inspired Henry with a desire to extend his knowledge of Africa. In 1416 he established at Sagres in SW Portugal a base for explorations, later adding a naval arsenal and an observatory and a school for the study of geography and navigation. The nearby port of Lagos provided a convenient harbor. One of his navigators rediscovered the Madeira Islands (1418–20), and by degrees the west coast of Africa was explored. Cape Bojador was reached in 1434, Cape Blanco was passed in 1441, and the Bay of Arguim was discovered in 1443. When Henry's captains returned with slaves and gold, African exploration, long derided, became very popular; from 1444 to 1446 between 30 and 40 vessels sailed for the W African coast under the prince's authority. His navigators discovered the Senegal River and rounded Cape Verde (1444) and finally (1460) reached a point near the present Sierra Leone. The abuses of the slave trade caused Henry to forbid the kidnapping of blacks in 1455. Henry played an important political role in the minority of Alfonso V, establishing his brother Pedro as regent. His position as grand master of the wealthy and powerful Order of Christ (Portuguese successor to the Knights Templars) increased his influence, and much of the revenue for his ventures was derived from his ecclesiastical tithes. His military reputation, dimmed by a disastrous expedition (1437) against Tangier, was recovered by a subsequent Moroccan campaign (1458), and he was offered the command of several foreign armies. Henry's chief importance, however, lay in his notable contributions to the art of navigation and to the progress of exploration, which provided the groundwork for the development of Portugal's colonial empire and for the country's rise to international prominence in the 16th cent.
- E. D. S. Bradford (1960), R. H. Major (1967), C. R. Beazley (1895, repr. 1968), and E. Sanceau (1969).