he enterprise of maritime expansion undertaken by the Perfect Prince included the voyages of two navigators in his service who played key roles in the discovery of a sea route to India: Diogo Cão (or Cam) and Bartolomeu Dias.

DIOGO CÃO
In 1482, when São Jorge da Mina castle, was being built in Africa, King John II decided to resume explorations of the African coast south of the Equator that had ended at Cape Catarina. The king entrusted this mission to his captain Diogo Cão.

Commanding two caravels, the navigator sailed from Lisbon before 31 August 1482. For the first time, he was taking with him inscribed stone pillars or padrões. These markers were to be erected on major landmarks along the coast to be explored.
During this voyage, Diogo Cão discovered a large river called the Poderoso (now the Zaire or Congo), from where he sent emissaries to contact an important indigenous ruler of whom he had heard. He erected the first pillar, dedicated to St. George, on a banks of this river ( 6° S). On 28 August 1483, he reached Cape Lobo (now Cape Santa Maria, 13° 6' ), where he set up the St. Augustine pillar. A bit further ahead, he reached the anchorage of João de Lisboa (Lucira Grande) which, according to several historians, he believed to be the

point where the West African coast rounds to the east at the southernmost tip of the continent. He then returned to the Zaire River. When he failed to find the Portuguese he had left there, he some Congolese people with him, promising to bring them back.
The caravels returned to Portugal in early April 1484, encountering natural obstacles such as the Benguela current and southeasterly winds. When he announced that he had reached the southernmost tip of the continent and probably come close to the coveted passage to the Indian Ocean, Diogo Cão was dubbed a knight, given an annuity, honored by the king with an addition to his coat of arms and raised to the rank of a nobleman.

The navigator set off on his second voyage with three caravels in the fall of 1485. His objectives were to return the Congolese people captured during his earlier voyage, continue his search for the southern tip of Africa, which he believed he had found earlier, and reach the Indian Ocean.
During this voyage, when he once again sailed past Cape Lobo, Diogo Cão realized his mistake: he had not reached the end of Africa.
CHe continued advancing south, and reached Monte Negro (now Pointe Noir, 15° 40’ 36’’ S), where he set up the first pillar for this voyage, and sailed to Cape Padrão (Cape Cross, 21° 46’ S), where he left the second and last pillar.
During this voyage he met the King of the Congo and had an inscription engraved in the stones of Yelala, nearly

160 km from the mouth of the Zaire, near its final navigable stretch. The text of the inscription tells us the names of the main figures in Diogo Cão’s fleet.
Near Serra Parda (Ponta dos Farinhões, 22° 10’ S), he began his return voyage to Lisbon, which he reached in late 1486. His mistake cost him the loss of royal favor, which is why his name disappeared thereafter from the chronicles of the time.

BARTOLOMEU DIAS
Bartolomeu Dias was the captain King John II chose to continue Diogo Cão’s discoveries. Meanwhile, the ruler obtained direct information on the Indian Ocean, its geography, ports and trade, through his squires

Pero de Covilhã and Afonso de Paiva.
An experienced navigator, Bartolomeu Dias commanded one of the caravels in the fleet that sailed under Diogo de Azambuja’s command to build Mina Castle in 1481.
During the first half of August 1487, his expedition, made up of two 50-ton two caravels and a supply boat, sailed from Lisbon with the objective of reaching the southern tip of Africa and the Indian Ocean.
Bartolomeu Dias commanded the flagship, whose pilot was Pero de Alenquer. The other caravel, the São Pantaleão, was commanded by João Infante and piloted by Álvaro Martins. The supply boat’s

como captain was Diogo Dias (Bartolomeu’s brother), and its pilot, João de Santiago.
The fleet reached southwestern Africa in October. There, he left the supply boat in a small bay (which may have been Alexander Bay or Baía dos Tigres) guarded by nine sailors.
On 6 January 1488, he reached Serra dos Reis (Cardow Berg). Continuing south, he lost sight of the shore. He then turned east but failed to find the coast as he expected. He had thus rounded the cape without having seen it. He veered to the north, arriving in an anchorage he called the Bay of Cowherds, probably what is now the Bay of St. Blaise or Mosselbaai, called Angra de São Brás by the Portuguese.

If this is where he arrived, he probably landed there on 3 February 1488. The expedition then continued moving eastward, exploring the coast as far as the Rio do Infante (possibly the Great Fish or Groot-Vis River), where it arrived in March 1488. There, Bartolomeu Dias ceded to his exhausted crew, who begged to return to Portugal.
On its return voyage, the fleet rounded the southern limit of Africa, which Bartolomeu Dias named the Cape of Storms (later renamed Cape of Good Hope by John II).
Three pillars were erected during this voyage. The only known fragments extant belonged to the St. Gregory pillar, set up on False Island on 12 March 1488.

At Salto Bay, they found just three of the sailors they had left guarding the supply boat. The rest had been killed by the indigenous peoples. The supplies were divided between the two caravels, the boat was burned, and the ships returned to Lisbon.
Before it entered the mouth of the Tagus in December 1488, the fleet stopped at Príncipe Island, Resgate River and Mina Castle. During this last stop, the return voyage may have been witnessed by Christopher Columbus, if he wrote the observation found in a copy of Imago Mundi that belonged to him, as most scholars believe he did. Henricus Martellus is thought to have used a similar map, now lost, in 1489, when he delineated part of the recently discovered South African coast in the planisphere he made in that year.

This is the first map we have found that shows the Cape of Good Hope, the definitive passage between the Atlantic and Indian oceans.