The Leie (Dutch) or Lys (French) is a river in France and Belgium, and a left tributary of the Scheldt. Its source is in Pas-de-Calais, France, and it flows into the river Scheldt in Ghent, Belgium. Its total length is Template:Convert.
It is a very polluted river due to the high density of population and industry in the North of France and in Belgium. Historically, the Lys valley was known for the spinning and weaving of flax. The region of the Leie (between Deinze and Ghent) used to be known as a favourite place for numerous painters in the first half of the twentieth century.
The source of the Lys is in the village Lisbourg, east of Fruges, in the Pas-de-Calais department of France. It flows generally northeast through the following departments of France, provinces of Belgium and towns:
- Pas-de-Calais (F): Thérouanne, Aire-sur-la-Lys
- Nord (F): Merville, Armentières, Halluin
- Hainaut (B): Comines-Warneton
- West Flanders (B): Menen, Kortrijk, Waregem, Wervik
- East Flanders (B): Zulte, Deinze, Ghent
The river Lys was the location of three battles between the Allies and the German Army. During the First World War in 1918 the location was the scene of the First Battle of the Lys, which was part of the German Spring Offensive, and later that year of the Second Battle of the Lys, which was part of the Allies' Hundred Days Offensive. During the Second World War the Battle of the Lys was part of the 1940 Nazi-German offensive in Flanders towards the English Channel.