After a reign, which ranks among the most glorious in Portuguese history, made famous by maritime discoveries and literary advancement, leaving behind him sons worthy and able to guide the people along the road of civilization to wealth and prosperity, John I., rightly surnamed "the Great," died at his palace at Lisbon on August 14, 1433, having survived his wife Philippa of Lancaster nearly twenty years.
Contrary to the expectation of his subjects, the reign of King Edward was but short, and it is marked only by a signal disaster. His own great qualities, and the promise he had given of being both a good and a great king when assisting his father, combined to raise the highest hopes, which were destined to be cruelly shattered. On ascending the throne he believed himself strong enough to take a step, intended to check the perpetuation of power in the hands of the feudal nobility, which had often been discussed between his father, his brother Dom Pedro, João das Regras, and himself, and in 1434 he summoned a full Cortes at Evora. He there propounded the "Lei Mental" or the provision, which was assumed to have been in the mind of King John when he made his extensive grants of land to the nobility, namely, that they could only descend in the direct male line of the original grantee, and should revert to the Crown on failure of such heirs. The law was carried by the influence of the king's brothers, in spite of the natural opposition of the nobility, who never forgave the supporters of the measure. In other matters Edward simply followed the example of his father. He continued the English alliance, ratified the treaty of Windsor, and was made a Knight of the Garter in his father's room; he maintained an attitude of prudent neutrality towards Castile; he encouraged the literary movement, represented by Fernan Lopes, and took an intelligent interest in the schemes and plans of his brother, Dom Henry.
But, unfortunately, the king's life was shortened and Dom Henry's explorations checked for a time by the fatal expedition to Tangier in 1437. This expedition was the natural sequel of the expedition to Ceuta, and was undertaken in opposition to the advice of the Pope, and of Dom Pedro. It was entirely the result of the earnest solicitations of the king's favourite brother, Dom Ferdinand. This pious young prince burned with crusading ardour; his one longing in life was to fight the infidels, and he could not appreciate the fact that Dom Henry was doing far greater work for the world in exploring the coast of Africa, than in killing Mohammedans. The ardour of Dom Ferdinand won the day, and King Edward collected a fleet and army in the Tagus, and sailed for the coast of Africa. The object of the attack was Tangier and it was most foolishly chosen. Ceuta was on the sea coast, and the Portuguese soldiers could use their fleet as a base of operations, and could retreat to it in case of need; whereas Tangier was three miles from the coast. As might have been foretold, when King Edward with his eight thousand Portuguese soldiers formed the siege of Tangier, the Moors at once cut off his communications with the fleet, and in three days the Portuguese army was reduced to extremities. It was only by Dom Ferdinand's willing sacrifice of himself as a hostage, that the troops were allowed to return to their ships and find their way back to Lisbon. This disaster and the captivity of his favourite brother so preyed upon King Edward's mind that he died in 1438. His death was happier than that of Dom Ferdinand, who, after a long and cruel imprisonment, borne with such heroic patience and exemplary piety, as to win for him the title of "the Constant Prince," died at Fez in 1443.