The Battle of the Arar was fought between the migrating tribes of the Helvetii and six Roman legions under the command of Gaius Julius Caesar in 58 BC.

When Caesar became governor of the provinces given to him by the Roman Senate, three of his four legions were in northeastern Italy guarding against potential threats from Thracian tribes.

[2] Shortly after he became governor, Caesar became aware that the Helvetii were planning to migrate to western Gaul as a result of the growing presence of Germanic tribes in their present home territory.

This caused the Helvetii to take an alternative route through the territory of the Aedui tribe and cross the river Arar (Saône) using rafts and boats.

As a result, Caesar quickly bridged the river Arar and pursued the Helvetii for over two weeks until he was forced to divert his army to the city of Bibracte to replenish provisions.