Aire-sur-la-Lys

History and description

A town of medieval origin, situated on the left bank of the Lys, Aire-sur-la-Lys was besieged on numerous occasions during the 16th-17th centuries, including one by Vauban in 1676, during the war of Holland. In 1540, the Spanish chose to erect their first modern constructions. These works were followed by the construction of ten ravelins, eight bastions and eight hornworks. The pentagonal Saint Francis fort was constructed in 1642. Falling to the French in 1676, Aire was absorbed into the second line of the Pré Carré in 1678.
Vauban established two projects of fortifications in 1686 and 1688. He also created a new fortified urban wall on the basis of the medieval fortifications to the east of the town. On the exterior, he retained the two hornworks. The fort Saint-François had its ramparts restored and was bolstered with barracks, officers’ quarters, a chapel, a powder keg, etc. The engineer Charles Robelin went on to add two ravelins restored and excavated at the end of the 17th century. The defensive arrangement was rounded off with flooded ditches filled with drains and streams converging toward the town. These works were carried out between 1680 and 1690. After 1740, other defensive improvements were set out: several ravelins were expanded and counterguards were added.