Christopher Columbus’s first voyage to the Americas threatened to intensify the rivalry between the Catholic kingdoms of Spain (Castile) and Portugal into open warfare. Both kingdoms wanted to claim all newly discovered lands that were not Christian, that is, not Catholic.
The Line of Demarcation was Pope Alexander IV’s solution to this problem. He issued the Bull of Demarcation to prevent Spain and Portugal from battling over new territories with resources such as gold. The bull successfully prevented a war between Spain and Portugal in the 16th century.
Neither the pope nor the Spanish or Portuguese actually knew what this line was dividing. The knowledge of the lands west of Europe was sketchy, and most people thought that the land Columbus had reached was part of Asia.
The pope may have believed that the Spanish would reach the same lands sailing west over the Atlantic that the Portuguese would reach sailing east around Africa. Previously in 1455, 1456, and 1481, popes had issued bulls about newly discovered land, although they had no knowledge of the actual geography of the earth.
The Roman Catholic nations left out of these bulls, including the French and Dutch, paid no attention to the papal decrees. The power of the Catholic Church in the Middle Ages had guided all international affairs in Europe up to the 15th century. France and Holland ignored the document, showing that the temporal power of the church was waning.
When Columbus returned from the Americas, he stopped in Portugal before going to back to the court of Ferdinand V and Isabella I of Spain. King João II of Portugal claimed the lands Columbus told him about even though the explorer had sailed for the Spanish monarchs.
Ferdinand and Isabella appealed to Pope Alexander VI, a Spaniard, for a solution. He issued the Inter caetera, the papal Bull of Demarcation, which was very biased toward Spain.
This document conferred all non-Christian lands found west of the designated line to Spain to explore and convert to Christianity. Portugal was to have all non-Christian lands east of the line. This decree in principle shut the Portuguese out of the Americas.
Dissatisfied, the Portuguese appealed to both the pope and Spain. Two more papal bulls followed—Examinae devotionis and another Inter caetera. These documents drew a line 100 leagues west of Cape Verde Islands.
Discoveries east of the line were to belong to Portugal, and discoveries west of the line were to belong to Spain. This resulted in Spain’s domination of all of South and Central America except Brazil, which the Portuguese claimed. The Treaty of Tordesillas modified the papal bull in 1494.
The Bull of Demarcation and later decrees gave the rights to colonize, exploit, and convert all non-Christian territory to Catholicism. These decrees treated all newly discovered nations and people as property and disregarded all non-Christian governments the Catholic explorers found.
Later the church realized these bulls were the cause of the enslavement and brutalization of native peoples and tried to emphasize peaceful, noncoerced conversion to Christianity. But it was too late; the system of Europeans’ forcibly taking control of non-Christian lands was already entrenched in the Americas, Africa, and Asia.
There have been modern movements for the revocation of these papal bulls. Indigenous peoples feel they were used for the subjugation of non-Christian indigenous peoples and should be rescinded to reflect modern thinking.
Certainly, the leaders in Rome could not have foreseen the horrendous decimation of native peoples that the conquest by the European powers caused. The Falkland War of the 1980s was in part justified by Argentina’s claim that the Falkland Islands is based on the Inter caetera. However, the Treaty of Madrid in 1750 annulled the boundary line.