Encouraged by the successful progress of Diego Cam in 1484 and 1485, King John became sanguine in his hopes of completing the discovery of a maritime route to India, around the continent of Africa, and determined upon using every exertion for this purpose. His first views were to endeavour to procure some information respecting India, by means of a journey overland; and with this object, Antonio de Lisboa, a Franciscan friar, together with a nameless lay companion, were dispatched to make the attempt of penetrating into India, through Palestine and Egypt. But, being ignorant of the Arabic language, these men were unable to penetrate beyond Jerusalem, whence they returned into Portugal. Though disappointed in this attempt, by the ignorance or want of enterprise of his agents, his resolution was not to be repressed by difficulties, and he resolved upon employing fresh exertions both by sea and land, for the accomplishment of his enterprise. He accordingly fitted out a small squadron under Bartholomew Diaz, a knight of the royal household, to attempt the passage by sea.
For this important enterprise, Bartholomew Diaz was only supplied with two small caravels of fifty ton each, accompanied by a still smaller vessel, or tender, to carry provisions. Of these vessels, one was commanded by Bartholomew Diaz, as commodore, the second caravel by Juan Infante, another cavalier or gentleman of the court, and Pedro Diaz, brother to the commander in chief of the expedition, had charge of the tender. The preparations being completed, Bartholomew sailed in the end of August 1486, steering directly to the southwards.
We have no relation of the particulars of this voyage, and only know that the first spot on which Diaz placed a stone pillar, in token of discovery and possession, was at Sierra Parda, in about 24°40'S. which is said to have been 120 leagues farther to the south than any preceding navigator. According to the Portuguese historians, Diaz sailed boldly from this place to the southwards, in the open sea, and never saw the land again until he was forty leagues to the east of the Cape of Good Hope, which he had passed without being in sight of land. The learned geographer, Major Rennel, informs us, that Sir Home Popham and Captain Thompson, while exploring the western coast of Africa in 1786, found a marble cross, on which the arms of Portugal were engraved, in latitude 26°37'S. near a bay named Angra Pequena: But, as the Portuguese long continued to frequent these coasts exclusively, and considered them all as belonging to their dominions under the papal grant, this latter cross, on which the inscription was not legible, may have been erected at a considerably subsequent period. At all events, the track of Diaz was far beyond the usual adventure of any former navigator, as he must have run a course of from seven to ten degrees of latitude, and at least between two or three degrees of longitude, in utterly unknown seas, without sight of land. The first land seen by Diaz is said to have been forty leagues to the eastward of the cape, where he came in sight of a bay on the coast, which he called Angra de los Vaqueros, or bay of herdsmen, from observing a number of cows grazing on the land. The distance of forty Portuguese leagues, would lead us to what is now called Struys bay, immediately east of Cabo das Agullias, which latter is in lat. 34° 50' S. and long. 20° 16' E. from Greenwich. From this place Diaz continued his voyage eastwards, to a small island or rock in the bay, which is now called Zwartkops or Algoa, in long. 27° E. on which rocky islet he placed a stone cross or pillar, as a memorial of his progress, and named it, on that account, Santa Cruz, or El Pennol de la Cruz. In his progress to this place from the Angra de los Vaqueros, he had set some Negroes on shore in different places, who had been brought from Portugal for this purpose, and who were well clothed, that they might be respected by the natives. These Negroes were likewise provided with small assortments of toys for bartering with the natives, and were especially charged to make inquiry as to the situation and distance of the dominions of Prester John. Of the fate of these Negroes we are nowhere informed, but may be well assured they would receive no intelligence respecting the subject of their inquiry, from the ignorant Hottentots and Caffres of Southern Africa.
It would appear that Diaz was still unconscious that he had reached and overpassed the extreme southern point of Africa, although now nearly nine degrees to the east of the Cape of Good Hope, and at least one degree back towards the north of his most southern range; but he may have supposed himself in a deep bite or bay of the coast, similar to the well– known gulf of Guinea. Under this impression, that he had not accomplished the grand object of his enterprize, he was anxious to continue his voyage still farther towards the east: But, as the provisions on board his two caravels were nearly exhausted, and the victualling tender under the command of his brother was missing, the crews of the caravels became exceedingly urgent to return, lest they might perish with famine. With some difficulty he prevailed on the people to continue their course about twenty-five leagues farther on, as he felt exceedingly mortified at the idea of returning to his sovereign without accomplishing the discovery on which he was sent. They accordingly reached the mouth of a river, which was discovered by Juan Infante, and was called from him, Rio del Infante, now known by the name of Great-Fish River, in about lat. 33°27' N. long. 28°20'E. The coast still trended towards the eastwards, with a slight inclination towards the north; so that, in an eastern course of about thirteen degrees, they had neared the north about six degrees, though still unsatisfied of having absolutely cleared the southern point of Africa.
From this river, the extreme boundary of the present voyage, Diaz commenced his return homewards, and discovered, with great joy and astonishment, on their passage back, the long sought for and tremendous promontory, which had been the grand object of the hopes and wishes of Portuguese navigation during seventy-four years, ever since the year 1412, when the illustrious Don Henry first began to direct and incite his countrymen to the prosecution of discoveries along the western shores of Africa. Either from the distance which the caravels had been from the land, when they first altered their course to the eastwards, or from the cape having been concealed in thick fogs, it had escaped notice in the preceding part of the voyage. At this place Diaz erected a stone cross in memory of his discovery; and, owing to heavy tempests, which he experienced off the high table land of the Cape, he named it Cabo dos Tormentos, or Cape of storms; but the satisfaction which King John derived from this memorable discovery, on the return of Diaz to Portugal in 1487, and the hope which it imparted of having opened a sure passage by sea from Europe through the Atlantic into the Indian ocean, by which his subjects would now reap the abundant harvest of all their long and arduous labours, induced that sovereign to change this inauspicious appellation for one of a more happy omen, and he accordingly ordered that it should in future be called, Cabo de boa Esperanзa, or Cape of Good Hope, which it has ever since retained.