Short answers, pulled from the story.
The Meuse is 925 kilometres long in total. It rises near Pouilly-en-Bassigny in the commune of Le Chatelet-sur-Meuse on the Langres plateau in northeastern France, then flows north through Belgium and the Netherlands before emptying into the North Sea via the Rhine-Meuse-Scheldt delta.
The Meuse and its crossings were a key objective during the Battle of France and the Battle of Sedan. The river was also a strategic target during the Battle of the Bulge, Germany's last major offensive on the Western Front, which took place in December 1944 and January 1945.
Lyrics written in 1841 described a then-disunited Germany with the Meuse as its western boundary, at a time when King William I of the Netherlands had joined the German Confederation with his Duchy of Limburg. Only the third stanza of the Deutschlandlied has been used as Germany's official anthem since 1952, and the first stanza containing the Meuse reference is omitted.
Mosasaurus, a Cretaceous sea reptile, was named after the Meuse because the first known fossils were discovered outside Maastricht in 1780. The Latin name of the river, Mosa, forms the root of the prehistoric creature's scientific name.
The separation of the Rhine and Meuse into distinct river systems was considered the greatest achievement in Dutch hydraulic engineering before the completion of the Zuiderzee Works and Delta Works. This involved damming the Meuse branch at Heusden and digging the canalised Bergse Maas in 1904 to replace a silted-up natural distributary.
France, Germany, Luxembourg, the Netherlands, and Belgium signed an international management agreement in Ghent in 2002. The Belgian regional governments of Flanders, Wallonia, and Brussels also participate. An International Commission on the Meuse oversees implementation of the treaty, with costs shared in proportion to each country's territory within the basin.