For most countries of Western Europe the fifteenth century – the epoch of the Hundred Years War and the Wars of the Roses – was a time of civil strife and/or fears of invasion. The Turks, who captured Constantinople in 1453, menaced the whole Levant and the Balkans, Spain, the only country that shares some of Portugal’s peninsular advantage (thought diluted by the competition of her prosperous Mediterranean ports), was torn by civil strife that for most of the century kept her near anarchy. Portugal, in sharp contrast to all these others, was a united kingdom for the whole of the fifteenth century and was hardly touched by civil disturbance.

“The Portuguese Discoverers”, from “The Discoverers”, Daniel J. Boorstin, The National Board for the Celebration of Portuguese Discoveries, Lisbon, 1987