The flag of Portugal during Prince Henry's life.

These expeditions were sent to create much-needed maps of the West African coast, to defeat the Muslims, to spread Christianity, and to establish trade routes. Prince Henry helped begin the Great Age of Discovery that lasted from the 1400's to the early 1500's.

Early Life: Prince Henry was the third son of King John I (João I) of Portugal and his English wife, Philippa of Lancaster. When he was 21, Prince Henry (with his father and brothers) attacked the Moslem port of Ceutha in north Morocco (in Africa, across the Mediterranean Sea). This successful attack in 1415 inspired Prince Henry to explore Africa, most of which was unknown to Europeans. Prince Henry was determined to see Portuguese sailors sail down the west coast of Africa to find the limits of the Muslim world (in order to defeat the Muslims), and to find the legendary Christian empire of the priest-king Prester John (who did not, in fact, exist). In 1419, his father appointed Prince Henry the governor of the province of Algarve (on Portugal's southern coast).

School of Navigation: About 1418, Prince Henry started the first school for oceanic navigation along with an astronomical observatory at Sagres, Portugal. In this school, people were trained in nagivation, map-making, and science, in order to sail down the west of Africa.

Exploring West Africa: At this time, no Europeans had sailed past the treacherous Cape Bojador and returned alive. Cape Bojador is on the coast of Africa just below latitude 27° North (off the western Sahara Desert) and had frequent, violent storms and strong currents. The Europeans called the ocean beyond that point the "Sea of Darkness." Most sailors refused to go there. Prince Henry sent 14 expeditions there over 12 years, trying to go farther than Cape Bojador. Prince Henry convinced Gil Eannes to try, and Eannes succeeded in 1434.

Gil Eannes: Gil Eannes was a Portuguese explorer who was the first European to sail beyond the dreaded Cape Bojador and return. Eannes worked in Prince Henry's household. On Eannes' first trip down the coast of Africa in 1433, he only sailed as far as the Canary Islands. In 1434, Eannes rounded Cape Bojador, and then landed on the coastal desert. He found no people there, only a few hardy plants, including "Saint Mary's roses," which he brought back to Portugal as proof of his accomplishment.

Eannes made another journey in 1435, again rounding Cape Bojador and sailing south; he sailed with Alfonso Goncalves Baldaya. About 50 leagues past the cape, they entered a large bay and saw a caravan of men and camels. Eannes named the river Rio de Ouro (meaning river of gold). Baldaya sailed farther south and collected thousands of seal skins; this was the first commercial cargo brought to Europe from that part of Africa.

Goncalves and Tristao: In 1441, Prince Henry became involved in the slave trade, when Antao Gonçalves returned from Rio de Ouro with captives. Nuno Tristao reached Cabo Blanco that same year.

Alvise da Cadamosto: Many years later, in 1455, Prince Henry sent the Venetian (from Venice, Italy) navigator Alvise da Cadamosto (1432?-1511?) on two expeditions. On the first, in 1455, Cadamosto reached the mouth of the Gambia River (in west Africa). On the second, in 1456, Cadamosto sailed up the Gambia river to the Geba River. He tried trading with the Africans but was unsuccessful. Cadamosto claimed to have discovered the Cape Verde Islands, but it is uncertain if he was the first one there.