A Most Holy War, By Mark Gregory Pegg

The ancient battlements of Carcassonne are one of the most impressive sights in France, but are largely a 19th-century fake. They owe more to "visionary medievalism than historical verisimilitude".

The original fortifications were destroyed in 1209 by massive catapults in Innocent III's Albigensian Crusade, a war that raged between Garonne and Rhone.

Pegg insists that the Cathars, the Manichean heretics and supposed target of the crusade, were invented "around 1900... utter fantasy." The crusade was real enough – and this is a compelling account – but it was a war against people "who looked and acted like Christians".