Prince Henry’s endeavours were crowned with partial success, though not in the reign of his father, for in 1434 Gil Eannes doubled Cape Bojador, and in 1436 Affonso Gonçalves Baldaya reached the Rio d’Ouro. The attention of “the Navigator” was, however, soon absorbed by the progress of political affairs at home, and he had for a time to abandon his schemes of exploration. He served with distinction in the unfortunate expedition to Tangier, and then played an important part in the events, which ended in confirming the power of his brother Dom Pedro, the Duke of Coimbra, as Regent of Portugal. This enlightened prince took the greatest interest in the African explorations, and he assisted Prince Henry with even greater ardour than King John or King Edward. These were the most successful years of Prince Henry’s career. In 1441 Antão Gonçalves went a hundred leagues further than the Rio d’Ouro, and in the same year Nuno Tristão, the greatest and most daring of all Prince Henry’s captains, reached the cape which closes on the south the sort of shoulder formed by North-west Africa, and named it the Cabo Branco or White Cape. He did more than this; he brought home several captives, including a native prince. The capture was hailed with enthusiasm, and from this time the slave trade on the coast of Africa really began. It is strange that Prince Henry “the Navigator” should have been the founder of the African slave trade, but so it was, and the reasons are not hard to find. The provinces of the Alemtejo and the Algarves had never been thoroughly populated since their conquest, and the great lords and religious military orders, the owners of those districts, had never been able to bring them properly under cultivation. Slavery was not regarded with the modern sentiment of abhorrence; it was the natural fate of prisoners of war, and flourished greatly in the neighbouring country of Morocco. Prince Henry and the Duke of Coimbra felt the need of procuring labour to cultivate the southern provinces, and it seemed quite natural to them to carry off the unfortunate savages of the African coast. This idea greatly impressed the Portuguese nobles with Prince Henry’s sagacity; they did not understand his schemes about discovering a direct route to India, but they highly appreciated the introduction of cheap forced labour. The commencement of the slave trade greatly favoured the progress of the Portuguese navigators; they no longer came home empty-handed, and exploring became a profitable as well as an adventurous business. In 1444 Lançarote, with a fleet of eight ships, went upon a slave-taking expedition, and brought home two hundred captives, who were set to work on the domains of the Order of Christ in the Algarves, and in 1445 the same captain sailed with a fleet of fourteen ships from Lagos and brought home a still larger body of unfortunate slaves. From this time forth the tracks made by the explorers were followed closely by the slave-dealers.