History: When, in 1492, Columbus first stumbled upon the Bahamas, he was no mere explorer pursuing scientific truth for its own sake.
His patrons were the Catholic kings of Aragon and Castile, Ferdinand and Isabella, who had just completed the conquest of Granada, the last Muslim stronghold in the Iberian Peninsula, and forced out of their kingdoms all Jews who refused to convert to Christianity.
In Dogs of God, his fourth book on medieval Europe, James Reston Jr attempts to show that Columbus's initial journey, still seen by many Americans as a hallowed event in their country's pre-history, was in fact part of a long and bitter war which saw an aggressive, fundamentalist power - Spain - destroy what Reston assumes uncritically was a tolerant and multi-cultural society, where Muslim, Christian and Jew lived in peace.
Maritime exploration was one face of the coin; the Inquisition's relentless pursuit of the suspect conversos - Jewish converts to Christianity and their descendants - was the other.
Dogs of God, despite its clumsy title, should be a topical book, issuing a necessary word of caution at a time when a clash of civilisations is seen by many as inevitable. It should be, in other words, a worthwhile piece of popular history, introducing as wide an audience as possible (especially in the author's native United States) to the intricate historical relationship between three great monotheistic religions and demonstrating that even behind what, at first glance, was a simple voyage of exploration, lay a terrible struggle for supremacy in which Christian Europe was neither tolerant nor passive.
What Ferdinand and Isabella expected from Columbus's journeys was wealth and power with which to crush Islam, recover Jerusalem, and usher in a new age.
Popular history, by its very nature, is freed from the minute accountability expected of its academic counterpart. But for that reason its authors carry a heavy responsibility; their task is to make accessible, and if necessary engaging, the work of professional historians, taking into account the latter's most recent findings. And it is here that Reston stumbles, sacrificing too much in his quest for a good story and constant, unrelenting, topicality. Where there should be caution and scepticism, there is certainty and uncritical use of sources, notably contemporary chronicles.
Reston's use of language, intended to provoke thought, is merely grating: the inaccurate and cumbersome siege artillery of the 15th century was not a "weapon of mass destruction"; the expulsion of the Jews from Castile and Aragon was not a "final solution"; and Torquemada might have been methodical, but he was not, as is hinted in this book, the Adolf Eichmann of his day. Calling a young princess a "lusty wench" is simply out of place.
Too often we are told what leading characters must have felt or thought, and too often there are great contradictions and omissions. Portugal is sometimes described as the nemesis of Spain (as if 15th-century Portuguese did not consider themselves to be Spanish, at the time a cultural and not a political concept), the Portuguese king being a battle away from control of the peninsula; at other times Portugal is a "small and isolated nation, forever threatened" by its larger neighbour. Five million maravedis (ancient Spanish coin) are described as "a pittance", but four million maravedis are "an enormous pile of money, truly worthy of a royal bribe".
And where Reston speaks of 3,000 innocents burned at the stake by the Inquisition in the years leading up to 1492, current academic estimates place the number of executions (including the burning of effigies of those who had fled before capture) only in the hundreds.
Missing are wider strategic considerations - such as the mounting threat of the Ottoman Empire to the whole Mediterranean world, including Ferdinand's Italian dominions - and a solid examination of religious belief in Europe at the time, notably the Church's explanation for the existence and even success of other faiths. Were Castile and Aragon unique in their intolerance, or were they merely exceptional by virtue of their religious mix?
Whatever the importance of Reston's ultimate goal, reviving the "Black Legend" of the Inquisition is not the way to encourage a fresh look at the world around us. The past does not always contain lessons for today.
• Filipe Ribeiro de Meneses lectures in the Department of History at NUI Maynooth and is currently a Government of Ireland Research Fellow in the Humanities and Social Sciences
• Dogs of God: Columbus, the Inquisition and the Defeat of the Moors By James Reston Jr Faber and Faber, 364pp. £20