The fleet left in July and in August they attacked Ceuta. Victory was fast and easy. Dom João I was probably in command of the operation but the Infante Dom Henrique distinguished himself in the battle and was rewarded with the dukedom of Viseu and the lordship of CovilhãWhile he was staying in Ceuta he learned from traders of the riches of the hinterland. Products like spices, rugs, gold and silver were brought by caravans that crossed the Sahara. Gold routes across the desert were thought to start off in Guinea on the African west coast.
He also heard about Prester John, the legendary christian priest-king whose kingdom was somewhere in Africa or the Orient and possessed tremendous wealth. The quest for Prester John was on.
In response to a petition from King João I, he himself master of the order of Aviz, the pope named Prince Henry as the
grand master of the Order of Christ, which had replaced the crusading order of the Templars in Portugal. For this 
reason, all of Prince Henry's ships bore a red cross on their sails. It did not mean that he took religious vows but he had to lead a chaste and ascetic life.
He had now access to the money of the order that largely financed his great discoveries, an enterprise that had as its declared object the conversion of pagans to Christianity. Religion and economics
(God and gold) went hand in hand.
Previously, in 1418, again at João's
request, the Pope had named the king's 18 year old son Prince João, as
grand master of the Order of Santiago.
The island of Porto Santo was the first discovery Prince Henry made. Two of his men, João Gonçalves Zarco and Tristão Vaz Teixeira, dropped anchor in its harbour and calculated its position. With the help of Bartolemeu Perestrello they went back in 1425 with colonists. From there, they went on to discover and colonize Madeira. Porto Santo was granted to Perestrello. Madeira was divided between Zarco and Teixeira.
Prince Henry made his base for sea exploration in the Western Algarve. According to leggend, Sagres became a centre for cartography and the science of navigation. In the port of Lagos, shipbuilders saw the development of a new type of ship, the caravel.
Prince Henry spent most of his time at Sagres, at court and at the headquarters of the Order of Christ in the northern city of Tomar.
Two of the three ships that Columbus used on his voyage were caravels, the Nina and the Pinta.
King Duarte petitioned Rome to have his youngest brother, Fernando, named master of Avis, which was granted in by the Pope
Gil Eanes sails around Cape Bojador (just south of the Canary Islands), to the south of which, according to Spanish sea-lore, was the Dark Sea where it was impossible to stay alive.
It took 15 expeditions between 1424 and 1434 to pass beyond Cape Bojador.
In 1435 Eannes went again, together with Afonso Gonçalves Baldaya. They made it another 300 kms further south and, on a beach, found footprints of men and camels.
On his next voyage in 1436, Baldaya reached an inlet wich he mistakenly took for the mouth of a large river in Senegal and named it Rio de Ouro (River of Gold).
On the death of Dom Duarte, his son Afonso V was still a child, and his brother Pedro, duke of Coimbra, had himself made regent instead of the widow, Leonor of Aragon.
During Dom Pedro's regency, Prince Henry starts constructing a new center of operations on the promontory at Sagres.
Prince Henry begins to build a new type of ship in Lagos, the caravel.
So far, Prince Henry had, besides his growing knowledge of the African coast, not much to show for his investments. The money for his expenses came mainly out of his own pocket or from the revenues of the Order of Christ.
Nuno Tristão, who led one of the expeditions, reached Cabo Branco with a newly desinged caravel.
Antão Gonçalves was the first one to capture natives from the land beyond Cape Bojador and bring them home. One of them was Adahu, a Tuareg, who told Prince Henry a lot about the African interior but he had never heard of Prester John.
Antão Gonçalves embarked on another expedition, taking Adahu with him. Gonçalves hoped to barter him for a number of black slaves. He received 10 slaves, some gold dust and, curiously, a large number of ostrich eggs.
King Henry VI of England awards Prince Henry the Order of the Garter.
Prince Pedro grants to his brother Prince Henry the monopoly in sailing, war and trade in the lands to the south of Bojador. Pedro also granted him the 'royal fifth' from the profits of all voyages. Prince Henry got permission to colonize the Azores, and this resulted in a considerable supply of timber, sugar and wheat to Portugal. He was about to reap the rewards for his determination. The support from Prince Pedro was doubtless a great help.
Nuno Tristão goes beyond Cabo Branco and discoveres the uninhabited island of Arguim, where the portuguese later would set up a trading post. By 1455, 800 slaves were shipped from Arguim to Portugal every year.
The skepticism with which some saw Prince Henry’s ventures disappeared. Lançarote de Freitas commanded the first expedition backed by private investors from Lagos. The six ships, each ship having a banner of the Order of Christ, brought back more than 200 natives to sell at the slave market in Lagos. Prince Henry, of course, received his fifth share but donated it to the Church.
Lançarote received knighthood from Prince Henry.
Sintra went looking for slaves in the Argium archipelago and was killed by the islanders, together with quite a few of his crew.
All of Prince Henry's captains were told to set up friendly relations with the inhabitants, but the lucrative slave trade often made them break the rules.
Initially slaves were captured through outrageous means, including kidnapping and banditry. Prince Henry ordered a change of practice, and so trading for slaves between Africans and Europeans became the norm.
Antão Gonçalves found the natives so suspicious that he could no longer do business. He left a man named João Fernandes to spend some time with them. An old Moor was taken to Sagres to be questioned.
In the same year, Nuno Tristão sailed far south of Cabo Branco.
Dinis Dias and Lançarote reach the mouth of the river Senegal.
Dias is given credit for first reaching Cape Verde (the cape not the islands).
Nuno Tristão finds João Fernandes near the Rio do Ouro, where he had been living with the nomadic tribesmen of the region.
Nuno Tristão sails up the river Gambia, is attacked and the natives kill him, together with most of his crew.
Dom Afonso V comes of age, and the Duke of Bragança tries to turn him against his uncles Prince Pedro and Prince Henry. Prince Henry attempted to resolve the fights between Dom Afonso and Prince Pedro but, torn between defending Prince Pedro and retaining his grants and privileges, he did not do enough.
During Prince Henry's lifetime, the farthest south sailed was by Álvaro Fernandes who sailed 600 km. beyond Cape Verde.
A fortress was constructed on the island of Arguim to serve as a base and to protect the explorers and traders against the hostility from the natives.
Cadamosto, on his expeditions, learned a lot about the natives and their trade habits, leaving a complete account of his voyages.
Cadamosto was a Venetian, one of several foreign merchants that by now took part in the explorations, sharing profits with Prince Henry.
Afonso V, finding no support for his planned crusade against Constantinople, decided to attack Alcácer-Sequer, a fortress between Ceuta and Tanger. Some 200 ships were involved in the operation. The Portuguese proved to be too much for the Moors who surrendered to Prince Henry.
Dom Afonso V granted the Order of Christ a 5% tax on all goods from the new African lands.
On November the 13th , in his villa in Sagres, dies the Infante Dom Henrique, notwithstanding his great revenues, heavily in debt. He was enshrined in the founders chapel of the Monastery of Batalha.