designed and maneuvered their vessels so skillfully that boarding was near impossible on open water. Following the beginning of the Gallic Wars, the Veneti fiercely resisted the Romans both on land and by sea during the period following Caesar's conquest of Gaul but before his invasion of Britain. They targeted the Romans for raiding and maintained positive trade relations with the Britons across the channel. Given the highly defensible nature of the Veneti sea strongholds, land attacks were frustrated by the incoming tide, and naval forces were left trapped on the rocks vulnerable when the tide ebbed. Their capital, Darioritum, in modern-day Vannes, was extremely difficult to attack from land. At first the Roman galleys, fighting in unfamiliar conditions, were at a great disadvantage and suffered defeats and setbacks. Julius Caesar gave Decimus Junius Brutus Albinus command of the Roman fleet and the Roman navy adopted new tactics in order to quell the activities of the Veneti once and for all. Instead of boarding or capturing ships, the Romans would simply set them on fire. The Roman fleet under Albinus subjected the Veneti to savage reprisals for their earlier defiance. This culminated in the Battle of Morbihan when the Romans succeeded in setting aflame and destroying the entire Gallic fleet in Quiberon Bay, with Caesar watching from the shore. Following this defeat, their maritime commerce and trade activities declined under the Roman Empire. Fortifications Large stores of slingstones aerodynamically shaped by adding clay have been found in the Southern British hillfort of Maiden Castle which indicates that slings must also have played a role in the conflicts between Celtic tribes there, probably in sieges. The La Tène period also saw the development of multivallate fortresses, protected by formidable earthworks as well as the Murus Gallicus and Pfostenschlitzmauer constructions. The larger settlements in Gaul were described by Julius Caesar as oppida and the term is now used to designate the large pre-Roman towns that existed all across Western and Central Europe, many of which grew from hill forts. There are over 2000 of these forts known in Britain alone. The Celtic circular wall of Otzenhausen is one of the biggest fortifications the Celts ever constructed. It was built by Celts of the Treveri tribe, who lived in the region north of the fort. The fort is located on top of the Dollberg, a hill near Otzenhausen in Germany, about 695 m