The Bull Aeterni Regis (Sixtus IV.). June 21, 1481.
This bull is a confirmation by Pope Sixtus IV. of the bulls Romanus pontifex ( 1455)1 and Inter caetera ( 1456),2 sanctioning Portugal's claims to exclusive rights in Guinea; and it also includes an important new concession, since it confirms that article in the recently ratified treaty of Alcaçovas3 whereby the sovereigns of Castile promised not to disturb Portugal in Guinea or in certain of the Atlantic islands or in Morocco. The weight of papal authority was thus brought to bear against any attempt on the part of Castile to evade her agreement.
Such a bull was of particular value to Prince John at this juncture. Apparently the first bull of this kind issued since the death of the Infante Henry in 1460, it marks the beginning of a new stage in the history of African exploration. The Portuguese government had for a long time ceased to push forward the southern expeditions, but in 1481 they were energetically resumed by Prince John, who, even in the lifetime of his father, was charged with the government of the places in Africa and received the revenues from the Guinea trade.4 Upon the death of Alfonso in August, 1481, the prince succeeded to the throne under the title of John II., and before the end of the year he despatched an expedition under Diogo d'Azambuja to build the fort at Elmina, on the Gold Coast.5
In 1482 he sent ambassadors to urge King Edward IV. of England to prevent his subjects from sailing to Guinea. At about the same time Edward petitioned the Pope to permit Englishmen to trade in any part of Africa.6
Text: MS. The original manuscript of the promulgated bull is in the National Archives in Lisbon, Coll. de Bullas, maço 26, no. 10.
Text: Printed. J. Ramos-Coelho, Alguns Documentos ( 1892), PP. 47-55 (from the text inserted in the confirmatory bull of 1514) ; L. M. Jordão, Bullarium Patronatus Portugalliae Regum ( 1868), PP. 47-52.____________________