Prince Henry's plan requires the circumnavigation of Africa.
His early voyages stay close to the African coast.
After repeated attempts, Gil Eanes finally rounds Cape Bojador on the west coast of Africa in present-day Western Sahara in 1434, a psychological, as well as physical, barrier that is thought to be the outer boundary of the knowable world.
After passing Cape Bojador, the exploration of the coast southward proceeds very rapidly.
In 1436 Gil Eanes and Afonso Baldaia arrived at the Senegal River, which they call the River of Gold because two Africans they had captured are ransomed with gold dust.
In 1443 Nuno Tristão arrives at the Bay of Arguin off the coast of present-day Mauritania.
These voyages return enslaved Africans to Portugal, which sparks an interest in the commercial value of the explorations, and a factory is established at Arguin as an entrepôt for human cargo.
In 1444 Dinis Dias discovers the Cape Verde Islands, at this time heavily forested, and Nuno Tristão explorea the mouth of the Senegal River.
In 1445 Cape Verde is rounded, and in 1456 Portuguese arrive at the coast of present-day Guinea.
The following year, they reach present-day Sierra Leone.
Thus, when Prince Henry dies in 1460, the Portuguese have explored the coast of Africa down to Sierra Leone and discovered the archipelagoes of Madeira, the Azores, and the Cape Verde Islands.
