BELGAE, a Celtic people first mentioned by Caesar, who states that they formed the third part of Gaul, and were separated from the Celtae by the Sequana (Seine) and Matrona (Marne). On the east and north their boundary was the lower Rhine, on the west the ocean. Whether Caesar means to include the Leuci, Treviri and Mediomatrici among the Belgian tribes is uncertain. According to the statement of the deputation from the Remi to Caesar (Bell. Gall. ii. 4), the Belgae were a people of German origin, who had crossed the Rhine in early times and driven out the Galli. But Caesar's own statement (B.G. i. 1) that the Belgae differed from the Celtae in language, institutions and laws, is too sweeping (see Strabo iv. p. 176), at least as regards language, for many words and names are common to both. In any case, only the eastern districts would have been affected by invaders from over the Rhine, the chief seat of the Belgae proper being in the west, the country occupied by the Bellovaci, Ambiani and Atrebates, to which it is probable (although the reading is uncertain) that Caesar gives the distinctive name Belgium (corresponding to the old provinces of Picardy and Artois). The question is fully discussed by T.R. Holmes (Caesar's Conquest of Gaul, 1899), who comes to the conclusion that "when the Reman delegates told Caesar that the Belgae were descended from the Germans, they probably only meant that the ancestors of the Belgic conquerors had formerly dwelt in Germany, and this is equally true of the ancestors of the Gauls who gave their name to the Celtae; but, on the other hand, it is quite possible that in the veins of some of the Belgae flowed the blood of genuine German forefathers." W. Ridgeway (Early Age of Greece, 1901) considers that the Belgic tribes were Cimbri, "who had moved directly across the Rhine into north-eastern Gaul." No definite number of Belgian tribes is given by Caesar; according to Strabo (iv. p. 196) they were fifteen in all. The Belgae had also made their way over to Britain in Caesar's time (B.G. ii. 4, v. 12), and settled in some of the southern counties (Wilts, Hants and Somerset). Among their towns were Magnus Portus (Portsmouth) and Venta Belgarum (Winchester).
In 57 B.C., after the defeat of Ariovistus, the Belgae formed a coalition against Caesar, and in 52 took part in the general rising under Vercingetorix. After their final subjugation, Caesar combined the territory of the Belgae, Celtae and Aquitani into a single province (Gallia Comata). Augustus, however, finding it too unwieldy, again divided it into three provinces, one of which was Belgica, bounded on the west by the Seine and the Arar (Saône); on the north by the North Sea; on the east by the Rhine from its mouth to the Lacus Brigantinus (Lake Constance). Its southernmost district embraced the west of Switzerland. The capital and residence of the governor of the province was Durocortorum Remorum (Reims). Under Diocletian, Belgica Prima (capital, Augusta Trevirorum, Trier) and Secunda (capital, Reims) formed part of the "diocese" of Gaul.
See A.G.B. Schayes, La Belgique et les Pays-Bas avant et pendant la domination romaine (2nd ed., Brussels, 1877); H.G. Moke, La Belgique ancienne (Ghent, 1855); A. Desjardins, Géographie historique de la Gaule, ii. (1878); T.R. Holmes, Caesar's Conquest of Gaul (1899); M. Ihm in Pauly-Wissowa's Realencyclopädie, iii. pt. 1 (1897); J. Jung, "Geographie von Italien und dem Orbis romanus" (2nd ed., 1897) in I. Müller's Handbuch der klassischen Altertumswissenschaft.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)