The treaty was chiefly valuable to the Portuguese as a recognition of the prestige they had acquired. That prestige was enormously enhanced when, in 1497–1499, Vasco da Gama completed the voyage to India. The tendency to secrecy and falsification of dates casts doubts about the authenticity of many primary sources. Several historians have hypothesized that John II may have known of the existence of Brazil and North America as early as 1480, thus explaining his wish in 1494 at the signing of the Treaty of Tordesillas to push the line of influence further west. Many historians suspect that the real documents would have been placed in the Library of Lisbon. Unfortunately, due to the fire following the earthquake of 1755, nearly all of the library's records were destroyed, but an extra copy available in Goa was transferred to Lisbon Tower of Tombo during the following 100 years. The Corpo Cronológico (Chronological Corpus), a collection of manuscripts on the Portuguese explorations and discoveries in Africa, Asia and Latin America, was inscribed on UNESCO’s Memory of the World Register in 2007 in recognition of its historical value "for acquiring knowledge of the political, diplomatic, military, economic and religious history of numerous countries at the time of the Portuguese Discoveries." While the Crown was thus acquiring new possessions, its authority in Portugal was temporarily overshadowed by the growth of aristocratic privilege. After the death of Edward, further attempts to curb the power of the nobles were made by his brother, D. Pedro, duke of Coimbra, who acted as regent during the minority of Afonso V of Portugal (1438–1447). 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 on 20 May 1449, D. Pedro was defeated and killed at the Battle of Alfarrobeira. 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 injured the royal prestige, for Afonso married his own niece, Joanna, daughter of Henry IV of Castile, and claimed the kingdom of Castile in her name. At the Battle of Toro, in 1476, he fought an indecisive battle that made him realize that his claims to the Castilian throne were not achievable. However, Portugal defeated Castile in the naval war (1475–79) of the same conflict (War of the Castilian Succession), capturing a large Castilian fleet -full of gold- in the Battle of Guinea (1478).