The rivalry and cultural differences between Gauls and Germans – the pre-Roman cultures that gradually evolved into France and Germany – were noted by Julius Caesar in his On The Gallic War. Romans, Carthaginians and many other cultures frequently employed Gaul tribesmen as guides and translators. The Gauls frequently raided Roman territory, most spectacularly in 397 BC, seizing Rome itself after the Battle of the Allia and accepting a sizeable ransom for the release of the city. Gaul itself had strategic importance both because of its geographic position as well as a source of revenue, mercenaries and slaves.