municipality, West Flanders province (province), western Belgium. It lies along the Yperlee (Ieperlee) River, south of Ostend. Ypres became a major cloth-weaving city in the Middle Ages, and together with Brugge and Ghent it virtually controlled Flanders in the 13th century. At that time it was reputed to have a population of 80,000. An unsuccessful but devastating siege of the city by the English in 1383 during the Hundred Years' War helped cause Ypres's decline, however, and by the late 16th century its population had dwindled to 5,000. The town was frequently besieged by the French in the 17th century.
Learn more about Ypres with a free trial on Britannica.com.