DOULLENS, a town of northern France, capital of an arrondissement in the department of Somme, on the Authie, 27 m. N. of Amiens by rail. Pop. (1906) 4495. It has a citadel of the 15th and 16th centuries which has often served as a state prison and is now used as a reformatory for girls. There are also a belfry of the 17th century and two old churches. The town is the seat of a sub-prefect and has a tribunal of first instance; it has trade in phosphates, of which there are workings in the vicinity, and carries on cotton-spinning and the manufacture of leather, paper and sugar. Doullens, the ancient Dulincum, was seat of a viscountship and an important stronghold in the middle ages. In 1475 it was burnt by Louis XI. for openly siding with the house of Burgundy. In 1595 it was besieged and occupied by the Spaniards, but was restored to France by the treaty of Vervins (1598).