The Unelli or Veneli (also Venelli) (Greek: Οὐένελοι) were one of the Armoric or maritime states of Gallia. (B. G. ii. 34, iii. 11.) Ptolemy (ii. 8. § 2) names Crociatonum the capital of the Veneli. The people occupied the peninsula of Cotantin or Cotentin, which is now comprehended in the department of Manche, except a small part which is included in the department of Calvados.
Caesar mentions them with the Veneti, Osismi, Curiosolitae, and other maritime states. The Unelli and the rest submitted to Publius Licinius Crassus in 57 BCE; but in 56 BCE it was necessary to send a force again into the country of the Unelli, Curiosolitae, and Lexovii. Quintus Titurius Sabinus had the command of the three legions who were to keep the Unelli and their neighbours quiet. The commander of the Unelli was Viridovix, and he was also at the head of all the forces of the states which had joined the Unelli, among whom were the Aulerci Eburovices and the Lexovii. The force of Viridovix was very large, and he was joined by desperate men from all parts of Gallia, robbers and those who were too idle to till the ground. The Roman general entrenched himself in his camp, and made the Galli believe that he was afraid and was intending to slip away by night. The trick deceived the Galli, and they attacked the Roman camp, which was well placed on an eminence with a sloping ascent to it about a mile (1.6 km) in length. On the Galli reaching the Roman camp exhausted by a rapid march up the hill and encumbered with the fascines which they carried for filling up the ditch, the Romans sallied out by two gates and punished the enemy well for their temerity. They slaughtered an immense number of the Galli, and the cavalry pursuing the remainder let few escape. This clever feat of arms is told clearly in the Commentaries.
The Unelli sent a contingent of 6000 men to attack Caesar at the siege of Alesia. (B. G. vii. 75.)
Crociatonum became the civitas of the Unelli after the Roman conquest. It was given the name of Constantia in 298 during the reign of Roman emperor Constantius Chlorus. The surrounding region, called in Latin the pagus Constantinus subsequently became known as the Cotentin Peninsula