The Menapii were a Belgic tribe dwelling near the North Sea, around present-day Cassel, during the Iron Age and the Roman period.
[4] Later that year, while Caesar made his first expedition to Britain, he sent two of his legates and the majority of his army to the territories of the Menapii and Morini to keep them under control.
[8] Carausius, the 3rd century commander of the Roman fleet who declared himself emperor of Britain and northern Gaul, was a Menapian, born in Batavia.
[9] A legion called the Menapii Seniores is mentioned in the Notitia Dignitatum, a 5th-century register of Roman government positions and military commands.
[14][15] The Gaulish ethnonym Menapii has been phonetically compared with Manapii, the name of a tribe from southeastern Ireland mentioned by Ptolemy in the 2nd century AD.
[21] Of these last three, the Marsaci appear to be mentioned in another place by Pliny as having a presence on the coast south of the delta, neighbouring the Menapii, within Gaul itself.
While in Pliny the Menapii do not stretch beyond the Scheldt, in Strabo's 1st-century Geographica, they are situated further away than the Nervii and on both sides of the Rhine near its outlets to the sea, apparently not far from the Germanic Sigambri.
In any case as mentioned above they bordered in Roman times upon the Toxandrians, who apparently lived in the north of the lands of the Nervii and Tungri.
[26] In the later Roman Empire, The Princeton Encyclopedia of Classical Sites reports that "Cassel was superseded as capital of the Menapii by Tournai after Gaul was reorganized under Diocletian and Constantine the Great.
[26] Their civitas, or administrative capital, under the Roman Empire was Cassel in northern France, and later this was moved nearer to a river in Tournai, in present-day Belgium, on the Scheldt.
The positions of such Roman tribal capitals frequently didn't correspond to the centre of a tribe's territory in pre-Roman political geography.
The economic activity of the Menapii was primally extraction of wool from sheep, and the fabrication of primitive cloths, and these were perfected while the Roman Reign in the Region.