Cosedia
COSE´DIAa place in Gallia, in the country of the Unelli. The Antonine Itin. places it on a road from Alauna ( Aleaume) to Condate ( Rennes). The Table gives a route from Coriallum ( Cherbourg) to Condate through Cosedia, which is the next place to Coriallum. D'Anville discusses the site of Cosedia without determining its position, for there is great difficulty about the distances. Some geographers take Cosedia to be La Cousinière;and there are other guesses.
[G.L]A plausible tradition links Constantia with Constantius Chlorus, who was first Caesar then emperor in A.D. 292-306. In the 4th c. A.D. the city appears in the Notitia provinciarum along with those of Lugdunensis secunda, and in the Notitia Dignitatum as the residence of the praefectus militum primae Flaviae. With the coming of Christianity it became the seat of a diocese, still in existence. Historians identify Constantia with Cosedia, mentioned in the Peutinger Table and the Antonine Itinerary. It was in the territory of the Unelli but apparently was not their capital before the conquest or during the Early Empire. In Diocletian's reign military necessity forced Alauna (Alleaume) or Crociatonnum (Carentan) to be abandoned in favor of Cosedia, which then changed its name.
The ancient settlement was built on top of a long, fairly steep hill 91 m high, and on part of its slopes. It was not thickly settled, and the houses were built chiefly of light materials; in the 1st c. A.D. The town covered 27-30 ha, but diminished in the next centuries. Two bath complexes have been located, but no important monument; some fragments of wall frescos have been found but no statues or inscriptions. The city plan does not follow the classical pattern; the Roman road from Coriovallum (Cherbourg) to Condate (Rennes) passes through it as well as several older roads. Traces of a mediaeval rampart can still be seen, but some remains of walls found near the cathedral suggest that there was a fortified redoubt in antiquity, covering ca. 1.5 ha. Ruins of an aqueduct seem to be mediaeval; a shallow water-bearing stratum formerly fed a number of wells. Commerce was facilitated by the proximity of the sea, 12 km away, and in the 1st c. the city imported considerable quantities of delicate pottery and amphorae from Italy and southern Gaul.
BIBLIOGRAPHYM. Le Pesant, “Les origines antiques de Coutances,” Revue du département de la Manche 17 (1963) 6-37.
M. LE PESANT