The Sambre is a river in northern France and in Wallonia, Belgium. It is a left-bank tributary of the Meuse, which it joins in the Wallonian capital Namur.
The source of the Sambre is near Le Nouvion-en-Thiérache, in the Aisne département. It passes through the Franco-Belgian coal basin, formerly an important industrial district. The navigable course begins in Landrecies at the junction with the Canal de la Sambre à l'Oise, which links with the central French waterway network. It runs 54 km and 9 locks 38.50m long and 5.20m wide down to the Belgian border at Jeumont. From the border the river is canalised in two distinct section over a distance of 88 km with 17 locks. The Haute-Sambre is 39 km long and includes 10 locks of the same dimensions as in France, down to the industrial town of Charleroi. The rest of the Belgian Sambre was upgraded to European Class IV dimensions in the immediate post-World War II period. It lies at the western end of the sillon industriel, which is still Wallonia's industrial backbone, despite the cessation of all coal-mining and decline in the steel industry. The river flows into the Meuse at Namur, Belgium.
The navigable waterway is managed in France by Voies Navigables de France and in Belgium by the Service Public Wallon - Direction générale opérationnelle de la Mobilité et des Voies hydrauliques


The Sambre flows through the following départements of France, provinces of Belgium and towns:


The 19th-century theory that the Sambre was the location of Julius Caesar's battle against a Belgic confederation, was discarded a long time ago, but is still repeated.
Heavy fighting occurred along the river during World War I, especially at the siege of Namur in 1914 and in the last month of the war Battle of the Sambre.