French–German (Franco-German) enmity (French: Rivalité franco-allemande German: Deutsch–französische Erbfeindschaft) was the idea of unavoidably hostile relations and mutual revanchism between Germans and French people that arose in the 16th century and became popular with the Franco–Prussian War of 1870–1871. It was an important factor in the unification of Germany and World War I, and was finally overcome after World War II, when under the influence of the Cold War cordial French–German relations became the key to European integration.
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 390/387 BC (390 BC being the traditional and 387 BC a probable year), 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.