 John Calvin was the Protestant leader of the city in the 16th century.Geneva first appears in history as an Allobrogian border town, fortified against the Celtic Helvetii tribe, which the Romans took in 121 BC.In 58 BC, Caesar, Roman governor of Gaul, destroyed the Rhône bridge at Geneva and built a 19-mile earthwork from Lake Geneva to the Jura Mountains in order to block the migration of the Helvetii, who "attempted, sometimes by day, more often by night, to break through, either by joining boats together and making a number of rafts ("ratis"), or by fording the Rhône where the depth of the stream was least" (De Bello Gallico, I, 8).