The Portuguese and the exploration of the 15th century African West coast
The Moors controlled the Trans-Sahara trade routes between West and North Africa. This gave the Moors control over much on the slave, gold, and spice trade from this area to Europe. The Portuguese at first were not as interested in the slave trade as much as the gold and spice trade the Moors were proprietors of. The hope of obtaining slaves may have been part of the initial quest but the need for vast amounts of slaves would not expand until later with the advent of the sugar plantations and mining in Brazil.
Prince Henry believed that the source of the gold was the coast of Guinea but in truth the gold came from remote area near the upper waters of the Senegal River and Volta River. (PG. 52)
Prince Henry convinced his father to attack Ceula which was on the north most point on the West African coast at the Straights of Gibraltar. The capture of this port would hopefully have two effects, reduce the attacks by Barbary Pirates on the towns of the Algarve on the southern Portugal coast and gain control of the trade routes of the Moors. The capture of Ceula was not a complete success; the Moors simply moved their trade centers further east to Algiers. It did help to reduce the attacks by the Barbary Pirates that had used Ceula as a home port but most of all Moorish prisoners told detailed stories of passage trains of merchants and camels carrying goods to exchange for gold and slaves in Timbuktu on the Niger River and Cantor on the Gambia. Hearing these stories Prince Henry was more determined to find a sea route to the source of this lucrative trade. To prepare for these ventures he established a headquarters on Cape Saint Vincent at Sarges in Portugal. Here he gathered astronomers, cosmographers, and promising ship captains. At Lagos he commissioned the building of the Caravel Ship which had a Lanteen (triangular) sail, these ships were lighter, faster, and could sail windward. These ships were superior for exploration to other ships of that time.
Prince Henry financed his ventures partly with his own investments. He had a monopoly of fishing for Tuna along the coast of the Algarve, he owned a fishery on the Targus, and from subsidies from the “Order of Christ”, a knightly association. As a Grand Master of the order he gained profits from fairs sponsored by the Order at Tomar as well as Houses and shops leased around the fairground.
The first ventures of the Portuguese under the direction of Prince Henry were the seizures of the deserted islands of Madeira and the Azores. The Azores lay off the coast of Africa at approximately 535 miles from the mainland from the coast of Morocco.
The Azores are a small cluster of islands in the Atlantic Ocean about 950 miles from Lisbon.
Prince Henry believed that they would be profitable ventures and to prevent Spanish expansion laid claim to these islands in the name of Portugal. After colonization of both Madeira and the Azores the islands produced Dyes from resins, Wax, Honey, and wood.
Prince Henry continued to send out expeditions down the coast of West Africa reaching Cabo Branco at the extreme northern coast of modern day Mauritania. In 1444 continuing south along the coast, Dinis Dias discovered the Senegal River and further on rounded Cabo Verde (Cape Verde) and realized the coast turned eastward.
The Slave Trade, Hugh Thomas 1997