The city of Sluis was created by a lock in the Zwin, the watercourse that once gave Bruges access to the sea. It was given the city charter by the Flemish count Gwijde van Dampierre in 1290. In the 14th century Sluis was very important as a foreshore of Bruges. In 1340 the first major battle of the Hundred Years War took place in Bay before Sluis, the Battle of Sluis, which ended in a catastrophic defeat of France. When Flanders rose in 1492 against the Roman-German King Maximilian of Austria, Sluis was besieged in vain by Philip of Cleves-Ravenstein. By 1550 the Zwin was no longer passable. Later, a canal Sluis-Damme-Bruges was dug, but the big ships did not come to Bruges. The heyday of Sluis was over too.
In the Eighty Years War, it was conquered in 1576 by the Dutch, 1587 by the Spaniards and 1604 again by Moritz von Nassau. The fortress builder Menno van Coehoorn had 1702 still new bastions and other fortifications to build, but in 1747 and 1794, the French knew Sluis twice take.