Mont Cassel

During the late Iron Age the hill of Cassel was inhabited by the Menapii, a Belgic tribe, who made the hill-top settlement the capital of a large territory extending from modern Calais to as far as the Rhine.^[2] The hilltop was probably used as an oppidum or hill fort.^[3] The Menapii were absorbed into the Roman province of Gallia Belgica in the first century B.C. Cassel was redeveloped as Castellum Menapiorum, the urban centre or civitas of the Menapii.^[4] The modern town and hill take their name from the Roman settlement.

In the first centuries A.D., Mont Cassel was close to an inlet of the North Sea, making the settlement vulnerable to attacks from sea. In 928 the town on top of the hill was destroyed by Viking raids.^[5]

By end of the 16th century Cassel had become a border town between France and the Spanish Netherlands.^[6] Cassel was annexed to France in 1678 under the terms of the Treaty of Nijmegen, which ended the Franco-Dutch War. The annexation led to the town's defences being dismantled. Mont Cassel was considered indefensible, as it was within easy firing range of the nearby Mont des Récollets, and it would have cost far too much to fortify both hills. In addition, without the proximity of the border, the town had lost its strategic significance.^[3]

During the early part of World War I Cassel served as the headquarters of Marshal Ferdinand Foch because of its strategic position near the northern end of the Western Front and to be closer to the Belgian headquarters at Veurne.^[1][7] From 1916-1918, Cassel was the headquarters for the British Second Army under Sir Herbert Plumer. The town avoided significant damage during the war, though it came under occasional shellfire when the Germans advanced to within 18 kilometres (11 mi) during the Battle of the Lys in April 1918.^[8]