Mosa
Mosa (Maas), a river of Gallia, which Caesar supposed to rise in the Vosegus (Vosges) within the limits of the Lingones. (B. G. 4.10.) This passage of Caesar, in which he speaks of the Mosa in the lower part of its course receiving a part of the Rhine, called Vahalis (Waal), is very obscure. This matter is discussed in the article BATAVI Dio Cassius writes the word in the form Μόσας (44.42); and Ptolemy (2.9.3) has the form Μώσα in the genitive.
Caesar (Caes. Gal. 6.33) says that the Scaldis (Schelde) flows into the Mosa; a mistake that might easily be made with such knowledge of the coast of Belgium and Holland as he possessed. The only branch of the Mosa which Caesar mentions is the Sabis (Sambre), which joins the Maas on the left bank at Charleroi in Belgium.
The Maas, called Meuse by the French, rises about 48° N. lat. in the Faucilles, which unite the Côte d'Or and the Vosges. The general course of the Maas is north, but it makes several great bends before it reaches Liège in Belgium, from which its course is north as far as Grave, where it turns to the west, and for 80 miles flows nearly parallel to the Waal. The Maas joins the Waal at Gorcum, and, retaining its name, flows past Rotterdam into the North Sea. The whole length of the Maas is above 500 miles.
From William Smith (ed.), Dictionary of Greek and Roman Geography. Text provided under a CC BY-SA license by Perseus Digital Library, http://www.perseus.tufts.edu, with funding from the National Endowment for the Humanities and Tufts University. Data accessed from https://github.com/PerseusDL/canonical-pdlrefwk/ on 17 October 2026.