Kept in the royal monastery of Alçobaça till late in the sixteenth century, though now irrecoverably lost, this treasure of Don Pedro's, like his "manuscripts of travel," would seem to have been used at the Sagres school till Prince Henry's death, and at least as early as 1431 its effect was seen in the first Portuguese recovery of the Azores. All the West African islands, plainly enough described in the map of 1428, were half within, half without the knowledge of Christendom, ever and anon being brought back or rediscovered by some accident or enterprise, and then being lost to sight and memory through the want of systematic exploration. This was exactly what the Portuguese supplied. The Azores, marked on the Laurentian Portulano of 1351, were practically unknown to seamen when, after eighty years had passed, Gonzalo Cabral was sent out from Sagres to find them (1431). He reached the Formiga group—the Ant islands,—and next year (1432) returned to make further discoveries, chiefly of the island Santa Maria. But the more important advances on this side were made between 1444-50, after the first colony had been planted twelve or fourteen years, and were the result of the Prince's theoretical correction of his captains' practical oversight. From a comparison of old maps and descriptions with their accounts, he was able to correct their line of sail and so to direct them to the very islands they had searched for in vain.
But as yet these results were far distant, and the slow and sure progress of African coasting towards Cape Bojador was the chief outcome of Pedro's help. In 1430, 1431, and 1432, the Infant urged upon his captains the paramount importance of rounding the Cape, which had baffled all his caravels by its strong ocean currents and dangerous rocks. At last this became the Prince's one command: Pass the Cape if you do nothing beyond; yet the years went by, King John of good memory died in 1433, and Gil Eannes, sent out in the same year with strong hopes of success, turned aside at the Canaries and only brought a few slaves back to Portugal. A large party at Court, in the Army, and among the nobles and merchant classes, complained bitterly of the utter want of profit from Henry's schemes, and there was at this time a danger of the collapse of his movement. For though as yet he paid his own expenses, his treasury could not long have stood the drain without any incoming.
Bojador, the "paunch" or "bulging Cape," 180 miles beyond Cape Non, had been, since the days of the Laurentian Portulano (1351), and the Catalan and Portuguese voyages of 1341 and 1346, the southmost point of Christian knowledge. A long circuit was needed here, as at the Cape of Good Hope, to round a promontory that stretched, men said, fully one hundred miles into the ocean, where tides and shoals formed a current twenty miles across. It was the sight or the fancy of this furious surge which frightened Henry's crews, for it plainly forbade all coasting and compelled the seamen to strike into the open sea out of sight of land. And though the discovery of Porto Santo had proved the feasibility and the gain of venturing boldly into the Sea of Darkness, and though since that time (1418) the Prince had sent out his captains due west to the Azores and south-west to Madeira, both hundreds of miles from the continent, yet in rounding Bojador there were not only the real terrors of the Atlantic, but the legends of the tropics to frighten back the boldest.
Most mariners had heard it said that any Christian who passed Bojador would infallibly be changed into a black, and would carry to his end this mark of God's vengeance on his insolent prying. The Arab tradition of the Green Sea of Night had too strongly taken hold of Christian thought to be easily shaken off. And it was beyond the Cape which bounded their knowledge that the Saracen geographers had fringed the coast of Africa with sea-monsters and serpent rocks and water unicorns, instead of place names, and had drawn the horrible giant hand of Satan raised above the waves to seize the first of his human prey that would venture into his den. If God made the firm earth, the Devil made the unknown and treacherous ocean—this was the real lesson of most of the mediæval maps, and it was this ingrained superstition that Henry found his worst enemy, appearing as it did sometimes even in his most trusted and daring captains.
And then again, the legends of Tropical Africa, of the mainland beyond Bojador, were hardly less terrible than those of the Tropical Ocean. The Dark Continent, with its surrounding Sea of Darkness, was the home of mystery and legend. We have seen how ready the Arabs were to write Uninhabitable over any unknown country—dark seas and lands were simply those that were dark to them, like the Dark Ages to others, but nowhere did their imagination revel in genies and fairies and magicians and all the horrors of hell, with more enthusiastic and genial interest than in Africa. Here only the northern parts could be lived in by man. In the south and central deserts, as we have heard from the Moslem doctors themselves, the sun poured down sheets of liquid flame upon the ground and kept the sea and the rivers boiling day and night with the fiery heat. So any sailors would of course be boiled alive as soon as they got near to the Torrid Zone.
It was this kind of learning, discredited but not forgotten, that was still in the minds of Gil Eannes and his friends when they came home in 1433, with lame excuses, to Henry's Court. The currents and south winds had stopped them, they said. It was impossible to get round Bojador.
The Prince was roused. He ordered the same captain to return next year and try the Cape again. His men ought to have learned something better than the childish fables of past time. "And if," said he, "there were even any truth in these stories that they tell, I would not blame you, but you come to me with the tales of four seamen who perhaps know the voyage to the Low Countries or some other coasting route, but, except for this, don't know how to use needle or sailing chart. Go out again and heed them not, for by God's help, fame and profit must come from your voyage, if you will but persevere."
The Prince was backed by the warm encouragement of the new King, Edward, his eldest brother, who had only been one month upon the throne when he bestirred himself to shew his favour to a national movement of discovery. King John had died on August 14, 1433 (the anniversary of Aljubarrota), and on September 26th, of the same year, by a charter given from Cintra, King Edward granted the islands of Madeira and Porto Santo, with the Desertas, to Henry as Grand Master of the Order of Christ.
With this encouragement the Infant sent out Gil Eannes in 1434 under the strongest charge not to return without a good account of the Cape and the seas beyond. Running far out into the open, his caravel doubled Bojador, and coming back to the coast found the sea "as easy to sail in as the waters at home," and the land very rich and pleasant. They landed and discovered no trace of men or houses, but gathered plants, "such as were called in Portugal St. Mary's roses," to present to Don Henry. Not even the southern Cape of Tempests or Good Hope was so long and obstinate a barrier as Bojador had been, and the passing of this difficulty proved the salvation of the Prince's schemes. Though again and again interrupted by political troubles between 1437 and 1449, the advance at sea went on, and never again was there a serious danger of the failure of the whole movement through general opposition and discontent.
In 1435 Gil Eannes was sent out again to follow up his success with Affonso Baldaya, the Prince's cupbearer, in a larger vessel than had yet been risked in exploration, called a varinel, or oared galley. The two captains passed fifty leagues—one hundred and fifty miles—beyond the Cape, and found traces of caravans, reached as far as an inlet they named Gurnet Bay, from its shoals of fish, and again put back to Lagos, early in the year.