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When John of Joinville joined the crusade led by Louis IX in 1248, he boasted an illustrious family pedigree. His grandfather had died on the third crusade; two uncles had joined the fourth crusade; his father had fought against the Albigensian heretics and in Egypt during the fifth crusade. Almost 100 years later, a pilgrim came across two old men by the Dead Sea. Both were French Templar knights who had been captured at the fall of Acre in 1291, had worked for the Egyptian sultan and had settled down to have families “in the southern Judean hills, entirely isolated and ignorant of events in the West”. Now they were brought back with their families to Europe where they were lionised and granted pensions.

These two very different snapshots hint at both the variety and the pervasiveness of the crusader experience as detailed by Christopher Tyerman, an Oxford don, in this coruscating and comprehensive history (which includes 28 pages of admirably lucid maps). It is more than 50 years since Steven Runciman, another Oxford historian, published his clasic three-volume history of the crusades, notable for its literary flair, in which he disdained them as a “tragic and destructive episode” and “the triumph of barbarism and superstition”. Although Runciman is still highly readable, his lofty moral tone now seems misplaced. This was already the case when I studied the crusades at school in the late 1970s, following the publication in English of the seminal revisionist study by the German historian Hans Eberhard Mayer, which argued that, while the crusades were the result of complex motives, they should be treated primarily as part of the efflorescence of medieval religious devotion. Like most modern interpreters, Tyerman follows Mayer’s lead in this regard.

Take the first crusade, which resulted in the Christian capture of Jerusalem in 1099 and the brutal slaughter of the city’s Muslim population. It “sprang from a culture of militant piety”, says Tyerman, and victory confirmed the crucesignati, “those who had accepted the sign of the cross”, in “their sense of battered righteousness”. Or take Oliver, a French nobleman and Cathar, who resisted the crusade against his fellow heretics in the 1220s before succumbing to monarchical and ecclesiastical authority when he joined Louis IX’s crusade in 1247, .and spent much of the next 30 years in Outremer, as the Latin kingdoms in Cyprus, Syria and Palestine were known.

Crusading is perhaps best understood not as a series of expansionist expeditions, foretelling later imperialist ventures, but as a spiritual and cultural phenomenon of which those expeditions were a component. To the medieval mind, crusading success could be measured as much in terms of the number of souls saved as of military triumph or territory accrued. More people listened to and were inspired by crusading preachers than ever departed for the Holy Land.

Tyerman finds contemporary comparisons illuminating. Hence the 11th-century Alfonso VI of Leon-Castile is described as a “racketeer”, and Count Thierry of Flanders, a 12th-century figure, as a “Holy Land addict”, while Louis IX of France is called “the Nelson Mandela of his day, a man of suffering, acquainted with grief, of seemingly unimpeachable integrity yet active in the temporal affairs of nations”. The occasional example of poetic licence is quite different from anti-historical thinking — a trap into which many historians are apt to tumble and that Tyerman studiously avoids.

Departing from Runciman’s orthodox indignation, Tyerman judges the sack of Constantinople resulting from the diversion of the fourth crusade “an atrocity, but in the terms of the day not a war crime”. The plunderers came away with “enough to fund a European state for a decade”, yet if they “had proceeded to the Holy Land the following spring, the fall of Constantinople may never have acquired its reputation for unique barbarism”. Although Tyerman acknowledges that the fourth crusade, in a winning phrase, “unstringed the lyre of universal order and degree”, he points out that the traffic in relics plundered from Byzantium “contributed to patches of economic prosperity across Europe”, funding improvements in infrastructure and even promoting increased religious devotion.

Yet long after the ignominy of the fourth crusade, the crusading ideal continued to resonate: “the relative scarcity of crucesignati was masked by cultural ubiquity”. Indeed, the author argues, “the century of renewed Christian occupation of Acre (after 1192) saw the golden age of crusading in terms of the number of military expeditions east, as well as the integration of crusading institutions into the lives of the Christian faithful”. Paradoxically, the more effectively crusades were preached, recruited, planned and funded, the less they achieved. Crusading had always been a useful tool for building consensus between kings and rebellious barons, but as crusading expeditions became more state-directed and less freelance enterprises they fell prey to distraction by a pope’s or a monarch’s separate political problems.

Unlike Runciman, Tyerman encompasses the Reconquest of Spain as well as wars against heretics and eastern Slavs and later manifestations of crusading activity. He is a dab hand at untangling the high politics and diplomacy of the various crusading expeditions; his evaluations of military and technological capability are never less than perceptive. But where he excels is in his understanding of the contagious impact of the crusader mentality on medieval society. Please don’t be daunted by the prodigious length or unwieldiness of this volume. Instead, be amazed at the depth and range of Tyerman’s scholarship, at the holding in perfect tandem of trenchant analysis and narrative brio, and savour his flashes of lacerating wit.

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