The Scheldt is a 350-kilometre-long (220 mi) river that flows through northern France, western Belgium, and the southwestern part of the Netherlands, with its mouth at the North Sea.

The headwaters of the Scheldt are in Gouy, in the Aisne department of northern France. It flows north through Cambrai and Valenciennes, and enters Belgium near Tournai. Ghent developed at the confluence of the Lys, one of its main tributaries, and the Scheldt, which then turns east. Near Antwerp, the largest city on its banks, the Scheldt flows west into the Netherlands toward the North Sea.

The Scheldt estuary has always had considerable commercial and strategic importance. Called Scaldis in Roman times, it was important for the shipping lanes to Roman Britain.

Access to the river was the subject of the brief Kettle War of 1784, and during the French Revolution shortly afterwards, the river was reopened in 1792. Once Belgium had claimed its independence from the Netherlands in 1830, the treaty of the Scheldt determined that the river should remain accessible to ships heading for Belgian ports. Nevertheless, the Dutch government would demand a toll from passing vessels until 16 July 1863.

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