The Cimbrian War, fought between the Roman Republic and the Proto-Germanic tribes of the Cimbri and the Proto-Germanic Teutons (Teutones), who have migrated from northern Europe into Roman controlled territory, and clash with Rome and her allies, is the first time since the Second Punic War that Italia and Rome itself has been seriously threatened.The timing of the war has a great effect on the internal politics of Rome, and the organization of its military.

The war contributes greatly to the political career of Gaius Marius whose consulships and political conflicts challenge many of the Roman republic's political institutions and customs of the time.

The Cimbrian threat, along with the Jugurthine War, inspires the Marian reforms of the Roman legions, which are to have a significant effect on the history of the later Republic.Rome eventually wins the protracted and bloody war — which inflicts heavier losses on the Roman armies than they have suffered since the Second Punic War — with the victories at Aquae Sextiae and Vercellae resulting in the almost complete annihilation of the two Proto-Germanic tribes.