Born in 1394, Henry the Navigator was the third son of John I of Portugal, the founder of the Aviz dynasty. His mother was Philippa of Lancaster, the daughter of John of Gaunt. In 1414 he is reported to have convinced his father to mount a campaign of conquest against the Muslim port of Ceuta, on the North African coast across the Straits of Gibraltar from Portugal. The city was conquered in August of 1415, and while there Henry saw the fruits of the Saharan trade routes, for Ceuta was a terminus for that trade. The trade dried up after Ceuta fell into Portuguese hands, however, and Henry became fascinated with tapping into that wealth, as well as with Africa in general, and the legend of Prester John.
With that in mind, legend says that in 1416 he established a village, Vilo do Infante ("Prince's Town"), at Sagres in far south-western Portugal (though some sources say it may have existed already). It rapidly grew into a high-tech (for the 15th century) base for exploration, with a naval arsenal, an observatory, and a school for the study of geography and navigation added over time. Jehuda Cresques, a noted cartographer, was invited to come to Sagres and compile geographic knowledge for Henry, a position he accepted. The nearby port of Lagos provided a convenient harbor, and became a centre for ship-building.
On May 25, 1420, Henry was appointed the governor of the Order of Christ, the Portuguese successor to the Knights Templar. This was a position Henry would hold for the remainder of his life, and as time passed he became more and more devoted to Christianity. For the purposes of his interest in exploration, however, the appointment was important as a source of funds through the 1440s.
Up until Henry, Cape Bojador was the most southerly European-known point on the coast of Africa. Gil Eanes, the commander of one of Henry's expeditions, was the first known European to pass it, in 1434. When John I died, Henry's eldest brother Duarte became king, and granted Henry a "royal fifth" of all profits from trading within the areas discovered as well as the sole right to authorize expeditions beyond Cape Bojador. When Duarte died five years later, Henry supported his brother Pedro for the regency during Alphonso V of Portugal's minority, and in return received a confirmation of this tax. Henry also arranged for the colonization of the Azores during the regency, and the caravel was used for the first time.
Using the new ship, the expeditions then pushed onwards. Cape Blanco was reached in 1441 by Nuno Tristão and Antao Gonçalves. The Bay of Arguim was seen in 1443; an important fort built was built there in about 1448. Dinas Dias soon came across the Senegal River and rounded Cape Verde in 1444. By then the southern boundary of the desert had been passed and from then on, Henry had one of his wishes fulfilled: the Muslim land trade routes across the western Sahara Desert were circumvented, and slaves and gold began pouring into Portugal. By 1452, the influx of gold was great enough that the first gold cruzados ("crusades") were minted. From 1444 to 1446 as many as forty vessels sailed from Lagos for Henry, and private mercantile expeditions were launched for the first time. By 1460 the coast of Africa had been explored as far as the present-day Sierra Leone, and at some time in the 1450s the Cape Verde Islands were discovered (Antonio da Noli claimed the credit).
Meanwhile, Henry was also involved in events closer to home. He was a primary organizer of the Portuguese expedition to Tangier in 1437. A disastrous failure, Henry's younger brother Fernão was captured, and died while still in captivity eleven years later. Henry's military reputation suffered as a result, and most of his last twenty-three years were concentrated on his exploration activities, or in Portuguese court politics.
Henry's impact on history is great, having arguably sparked the European interest in colonial exploration that would so transform the world for the next four centuries. The school at Sagres was responsible for several advances in the art of navigation, and the discoveries made possible by Henry provided the groundwork for the development of Portugal's colonial empire. Within thirty years of his death, the Cape of Good Hope was rounded, and Vasco da Gama reached India a decade later. Brazil was discovered within another decade still. Christopher Columbus also spent some time in and around the school at Sagres, and while there is no record of his being formally associated with it, he did spend the late 1470s sailing around the Portuguese possessions of Madeira and on the African coast.