The background to European entry into the Pacific must include the ancient and never-healed rivalry between Portugal and Castile. In 1479 the Treaty of Alcaçovas liquidated the unfortunate Portuguese intervention in the Castilian succession; Portugal recognised the Spanish possession of the Canaries, but secured the other eastern Atlantic islands and an exclusive free hand along the African coast—not that this stopped interloping by other merchant adventurers, including Spaniards, though this became more hazardous after the building of the massive Portuguese fortress at El Mina (in Ghana) in 1481–2. Conflict, or at least hostility, between the two powers never quite ceased, despite dynastic marriages and the ground-rules established by the Treaties of Tordesillas in 1494 and Zaragoza in 1529, which set the geopolitical pattern in the earlier Iberian phase of Pacific history.

Whether the plans presented by Christopher Columbus in 1483–4 to the new and energetic King of Portugal, D. João II, pointed directly to Cathay and the Indies, or merely to Atlantic islands, has been, like every other aspect of his life and achievements, the occasion of intense controversy, much of it pointless in a broad view.^[1] On the one hand, the trifling trade goods such as beads, mirrors, needles, and the like which, according to las Casas, Columbus demanded were hardly appropriate to commerce with the immensely rich empires of the East; on the other hand, when he did sail he carried a letter from Ferdinand and Isabella addressed to the Great Khan of Cathay.^[2] In any case, the expert committee which D. João appointed to examine the proposal would have had no difficulty in demolishing Columbus's wild cosmography, while the would-be- 26 -discoverer, never one to undervalue the claims of a divinely-appointed pioneer, demanded exorbitant terms. Talk of islands to be found beyond the Azores had been in the air for generations, and in Portugal the immediate result of Columbus's initiative seems to have been merely a mild flurry of interest and official support—all aid short of financial—for voyages which would have the advantage, from D. João's point of view, of being by Portuguese subjects at their own expense. Nothing came of these, but the scale of the 1486 project of Fernão Dulmo—a voyage of six months—and the phrase ‘ilhas ou terra firme per costa’ (‘islands or a continental coast’) in the royal warrant, are significant as suggesting knowledge or presumption of a trans-Atlantic mainland, and this in turn was a possible or even probable factor in the Portuguese stance on shifting the ‘Line of Demarcation’ at Tordesillas.^[3] Meanwhile, the royal resources were devoted to the more serious purpose of opening the African route to the Indies, made a certainty by Dias in 1488.

On 4 March 1483, however, the man whom D. João had written off as ‘a man talkative and vainglorious … more fantastic with his imaginings of his Ilha Cipango than certain of what he said’^[4] (an accurate description, as far as it went) came across Lisbon bar, bringing gold and natives from ‘Antilha and Cipango.’ This time the result for Portugal was a diplomatic crisis. Fears that Columbus had been poaching in Guinean waters were soon dispelled, and despite some anxiety at the sight of natives who clearly were not from Africa, the Portuguese were not slow in discounting his claims to have discovered Japan or the real Indies. But obviously Castile was likely to follow up this striking success, and from the Portuguese point of view the whole balance of the globe might be upset.

The initial reaction was bellicose, the fitting out of a squadron with the implied threat of falling on any further Spanish expedition. But the Spain of 1493, flushed with the conquest of Granada, was much stronger than that of 1479, when Ferdinand and Isabella were only beginning to consolidate their grip on the joint kingdoms of Aragon and Castile, and for the moment D. João's bluff was called: he had at least served notice that his claims could not be ignored. However, the Spanish monarchs were in the happy position of being able to call the spiritual arm to their aid. By immemorial prescription, only the Papacy could authorise missions to heathen lands, and naturally such authority was normally accorded to specific rulers or religious Orders: the Bull Pontifex Romanus of 1455 was accorded to Prince Henry in his capacity as Governor of the Order of Christ, itself a survival from the Reconquista of the Peninsula. The salvation of unbelievers, obviously, might depend on secular strength, and that in turn on economic resources; mission rights, at least in the view of their recipients, carried with them as a necessary corollary rights of exploitation, and these could be best secured, perhaps only secured, by a monopoly in favour of the power behind the mission. This was the thinking behind Pontifex Romanus, ‘the charter of Portuguese imperialism’, which confirmed in the clearest terms the exclusive rights of the Crown of Portugal, and Henry as its agent, to discovery, conquest and- 27 -commerce south of Cape Bojador and as far as the Indies. The labourer in the vineyard was worthy of his hire.^[5]