The Belgae were naturally interested in cross-Channel trade with their kinsmen in north-east France, while the tribes of south-west England were concerned to maintain contacts with north-western France, where the sea-faring Venetii of Brittany were already a dominant power and completely controlled the old tin routes to Cornwall. When Julius Caesar advanced against the Venetii in 57BC they submitted to his rule, but the thoughts of Roman competition induced a quick change of mind. They revolted against Roman control and turned to the British Belgae to assist them in their struggle. Julius Caesar had a very tough campaign on his hands against their great Atlantic fleet and their forts perched on cliff promontories. However, Caesar won victory in Quiberon Bay as Caesar achieved naval supremacy in the Channel.