 Their attempts to amass power as "Populares" were opposed by the "Optimates" within the Roman Senate, among them Cato the Younger with the frequent support of Cicero.Caesar rose to become one of the most powerful politicians in the Roman Republic through a string of military victories in the Gallic Wars, completed by 51 BC.During this time he both invaded Britain and built a bridge across the Rhine river, greatly extending Roman territory.