Ferdinand had been the last legitimate descendant of Count Henry of Burgundy. With John I. began the rule of a new dynasty, the House of Aviz. The most urgent matter which con fronted the king—or the group of statesmen, led by Joao das Regras and the "Holy Constable" who inspired his policy—was the menace of Castilian aggression. But on Aug. 14, 1385, the Portu guese army, aided by 500 English archers, utterly defeated the Castilians at Aljubarrota. In October the "Holy Constable" won another victory at Valverde ; early in 1386 5,00o English soldiers, under John of Gaunt, reinforced the Portuguese ; and by the treaty of Windsor (May 9, 1386), the alliance between Portugal and England was confirmed and extended. Against such a combi nation the Castilians were powerless; a truce was arranged in 1387 and renewed at intervals until 1411, when peace was concluded. D. Diniz, eldest son of Inez de Castro, claimed the throne and invaded Portugal in 1398, but his supporters were easily crushed. At home John I. endeavoured to reform administration, to encour age agriculture and commerce, and to secure the loyalty of the nobles by grants of land and privileges so extensive that, towards the end of his reign, many nobles who exercised their full feudal rights had become almost independent princes. Abroad, he aimed at peace with Castile and close friendship with England. In 1387 he had married Philippa of Lancaster, daughter of John of Gaunt ; Richard II. sent troops to aid in the expulsion of D. Diniz; Henry IV., Henry V. and Henry VI. of England successively ratified the treaty of Windsor ; Henry IV. made his ally a knight of the Garter in 1400. The convent of 134talha (q.v.), founded to commemorate the victory of Aljubarrota, is architecturally a monument of the English influence prevalent at this time throughout Portugal.
The cortes of Coimbra, the battle of Aljubarrota and the treaty of Windsor mark the three final stages in the consolidation of the monarchy. A period of expansion oversea began in the same reign, with the capture of Ceuta in Morocco in 1415.
The Period of Discoveries: 1415-1499.—As the south-west ernmost of the free peoples of Europe, the Portuguese were the natural inheritors of that work of exploration which had been car ried on during the middle ages, chiefly by the Arabs. They began where the Arabs left off, by penetrating far into the Atlantic. The long littoral of their country, with its fine harbours and rivers flow ing westward to the ocean, had been the training-ground of a race of adventurous seamen. It was impossible, moreover, to expand or reach new markets except by sea. The long struggle to expel the Moors, with the influence of foreign Crusaders and the military orders, had given a religious sanction to the desire for martial fame.
It was the genius of Henry of Portugal (q.v.) that co ordinated and utilized all these tendencies towards expansion. Prince Henry placed at the disposal of his captains the vast re sources of the Order of Christ (the Portuguese branch of the Knights Templars, reformed and renamed in 1319), the best in formation and the most accurate instruments and maps. On land he again defeated the Moors, who attempted to re-take Ceuta in 1418; but in an expedition to Tangier, undertaken in 1436 by King Edward (1433-38), the Portuguese army was defeated, and could only escape destruction by surrendering as a hostage Prince Ferdinand, the king's youngest brother. Ferdinand, known as "the Constant," from the fortitude with which he endured captivity, died unransomed in 1443. By sea Prince Henry's captains con tinued their exploration of Africa and the Atlantic. In 1433 Cape Bojador was doubled; in 1434 the first consignment of slaves was brought to Lisbon; and slave-trading soon became one of the most profitable branches of Portuguese commerce. The Senegal was reached in 1445, Cape Verde was passed in the same year, and in 1446 Alvaro Fernandes pushed on almost as far as Sierra Leone. This was probably the farthest point reached before the Navigator died (146o). Meanwhile colonization progressed in the
Azores and Madeira, where sugar and wine were produced; above all, the gold brought home from Guinea stimulated the com mercial energy of the Portuguese. Under Alphonso V., surnamed the African (1443-81), the Gulf of Guinea was explored as far as Cape St. Catherine, and three expeditions (1458, 1461, 1471) were sent to Morocco; in 1471 Arzila and Tangier were captured from the Moors. Under John II. (1481-95) the fortress of Sao Jorge da Mina, the modern Elmina (q.v.), was founded for the protection of the Guinea trade in 1481-82; Diogo Cam, or Cao, discovered the Congo in the year 1482 and reached Cape Cross in 1486; Bartholomeu Diaz doubled the Cape of Good Hope in 1488, thus proving that the Indian ocean was accessible by sea. After 1492 the discovery of the West Indies by Columbus rendered desirable a delimitation of the Span ish and Portuguese spheres of exploration. This was accomplished by the treaty of Tordesillas (June 7, which modified the delimitation authorized by Pope Alexander VI. in two bulls issued on May 4, 1493. The treaty gave to Portugal all lands which might be discovered east of a straight line drawn from the Arctic Pole to the Antarctic, at a distance of 370 leagues west of Cape Verde. Spain received the lands discovered west of this line. On its pro visions were based both the Portuguese claim to Brazil and the Spanish claim to the Moluccas (see MALAY ARCHIPELAGO: History).
After the death of Edward further attempts to curb the power of the nobles were made by his brother, D. Pedro, duke of Coim bra, who acted as regent during the minority of Alphonso V. (1438-47). The head of the aristocratic opposition was the duke of Braganza, who contrived to secure the sympathy of the king and the dismissal of the regent. The quarrel led to civil war, and in May 1449, D. Pedro was defeated and killed. Thenceforward the grants made by John I. were renewed, and extended on so lavish a scale that the Braganza estates alone comprised about a third of the whole kingdom. An unwise foreign policy simultaneously in jured the royal prestige, for Alphonso married his own niece, Joanna, daughter of Henry IV. of Castile, and claimed that king dom in her name. At the battle of Toro, in 1476, he was defeated by Ferdinand and Isabella, and in 1478 he was compelled to sign the treaty of Alcantara, by which Joanna was relegated to a con vent. His successor, John II. (1481-95) reverted to the policy of matrimonial alliances with Castile and friendship with England. Finding, as he said, that the liberality of former kings had left the Crown "no estates except the high roads of Portugal," he deter mined to crush the feudal nobility and seize its territories. The leader of the nobles, Ferdinand, duke of Braganza, was beheaded for high treason in 1483 ; in 1484 the king stabbed to death his own brother-in-law, Ferdinand, duke of Vizeu; and 8o other mem bers of the aristocracy were afterwards executed. Thus John "the Perfect," as he was called, assured the supremacy of the Crowri. He was succeeded in 1495 by Emanuel (Manoel) I., who was named "the Great" or "the Fortunate,"-because in his reign the sea route to India was discovered and a Portuguese empire founded.