Artois (ärtwäˈ) [key], region and former province, in Pas-de-Calais dept., N France, near the English Channel, between Picardy and Flanders. Arras is the chief city. Largely agricultural, it contains diverse industries, and occupies part of the once-productive Franco-Belgian coal basin. Owned in the Middle Ages by the counts of Flanders, Artois was annexed (1180) to France by Philip II through marriage. Burgundy gained (14th cent.) the territory, also through marriage. Later it was under Austrian rule, and from 1493 until its conquest (1640) by Louis XIII it was under Spanish rule. Confirmation of French possession was made by the Peace of the Pyrenees (1659) and the Treaty of Nijmegen (1678). Renowned for its états (assembly), which met until the 18th cent., it declined in political importance thereafter. Of strategic significance in World War I, it was the scene of heavy fighting. The region gives its name to the artesian well, known there for centuries.