Stephen O’Shea’s book is his third about the medieval period when religious wars raged in Europe, especially in the south of France. Catharism arose and found many followers in all social classes in the Languedoc, a region culturally and linguistically different from France that came under French control in 1228.

Cathars were Christian but the tenets of their faith — rejection of the Sacraments and the concepts of Hell or Purgatory, for example — were deeply heretical to Catholic orthodoxy. The ascetic Cathars saw the Church as corrupt, its rituals useless and its theology far removed from the first-century Christianity that the Cathars sought to emulate. The Church, viewing Catharism as a serious threat, first tried to bring its adherents back into the fold, but turned to violence in 1209 when these efforts failed.

The Church hunted down these lapsed Catholics, torturing and burning them by the hundreds. Open warfare broke out in the Languedoc and elsewhere in the south of France as forces loyal to Pope Innocent III and to King Philip II besieged and destroyed whole towns that harbored Cathars. This deadly expression of religious hatred was called the Albigensian Crusade, named for Albi, a city not far from Carcassonne.

By 1229, a treaty was signed intending to end the armed conflict of the Crusade. Few Cathars were visible in this battle-scarred region where people of all classes were sick of decades of conflict and simply wanted peace. Despite the treaty, the violence against the Cathars continued. Pope Gregory IX, who created the papal inquisition, directed the Franciscans’ rival order, the Dominicans, to appoint inquisitors in the Languedoc and the organized persecution was reinvigorated in 1232, albeit focused on individual “heretics” rather than on entire villages under the guise of religion. Residents of Carcassonne tried repeatedly to end this persecution and in 1299 a leader emerged who could do so.

This man was Bernard Délicieux, an articulate and educated friar in the Franciscan convent in Carcassonne. Bernard’s resourcefulness and unstinting efforts to repel the Church’s repression were heroic. This determined priest, whose story is recounted in carefully kept archives of the inquisition, fought tirelessly to protect his people, keep them out of the dreaded prison called the Wall and thwart the inquisitors. Bernard, a gifted orator, was charismatic and indefatigable, appealing repeatedly to King Philip the Fair, who intervened intermittently, temporarily curtailing the inquisitors.

Philip the Fair ruled uneasily from Paris, a realm much smaller and weaker than it would become, as both England and the Holy Roman Empire held large swaths of what grew into the French nation. These three centers of temporal power wrestled among themselves for hegemony, their struggles roiling the Continent. Papal power often prevailed in these conflicts, carrying with it the threat of excommunication should any ruler question whether any pope’s authority was temporal as well as spiritual.

By 1317, after sparring with the inquisition and the Church hierarchy for decades, Bernard — at least in part due to his effrontery — lost royal support because France needed to stabilize its relationship with Pope John XXII, a Dominican and forceful proponent of the inquisition, now resident in nearby Avignon. Inevitably, the noose tightened around Bernard. Sustained only by his faith and wits, he was finally imprisoned. After a show trial, whose records allow O’Shea to recreate the drama, Bernard was defrocked, tortured and finally condemned. The gallant priest died in 1320 in the hated Wall, another of the countless victims of the religious intolerance that fostered the inquisition.

Some readers may be daunted to find a lengthy eight-page list of dramatis personae, which this reviewer needed to consult frequently to follow the story. Perhaps in an effort to be hip — probably not achievable by a medievalist — or perhaps due to an editor’s lapse, the author regrettably employs jarring modern expressions like “flip side” in his narrative, which distracts the reader from the textured historical tableau he presents. This flaw does not, however, keep The Friar of Carcassonne from being a tasty read for a history buff who will come away with a new hero and a deeper understanding of a tumultuous time.

Penelope Farthing practices law in Washington. She is a Hoosier and holds degrees from Purdue and from Indiana University’s Maurer School of Law.