At the time of theGauls,Tarwanna orTervanna was the capital of theBelgian tribe of theMorini. After theRomans conquered Gaul, they too made the city the capital of theCivitas Morinorum district.
The origin of the name has several theories. According to the historian Malbracq, it got its name from its founder "Lucius Tauruannus",[5] others say it is derived from "Terra avanae" The land of Oats. But this second derivation seems to be a generic used term.[6]
Thanks to that ecclesiastical control of some of the most prosperous cities north of theAlps, likeArras andYpres, the bishopric was able to build acathedral which was at the time the largest in France.
The town was captured by theEmperor Maximilian andHenry VIII from the French in 1513 after theBattle of the Spurs. In 1553Charles Vbesieged Thérouanne, then a French enclave in theHoly Roman Empire, in revenge for a defeat by the French atthe siege of Metz. After he captured the city he ordered it to be razed, the roads to be broken up, and the area to beploughed andsalted.[dubious –discuss][7] Only a small commune which lay outside the city walls, then named Saint-Martin-Outre-Eaux, was left standing, and later (probably around 1800) took over the nameThérouanne. Part of the portal of the cathedral was acquired by Saint-Omer; a colossal statue of Christ is all that is left of it these days.
The ruin of the Abbey of St. Jean-du-Mont contains the remnants of agothic cathedral which has a seventh century Episcopal group and aCarolingian building, which are aregistered historical monument[8]
The town appears as Taruenna in a novel about an English pilgrimage to Rome byMatthew Kneale.[9]
InHilary Mantel's novelWolf Hall the first conversation between the central characterThomas Cromwell andHenry VIII, about the futility of war, sees Henry chide Cromwell for describing Thérouanne as a 'dog hole' in a speech in parliament opposing funds for a new expedition in France.[10]