Seven Days: From Rome to the Rhône
March 58 BC: the Helvetii set out west, and Caesar rides from Rome to the Rhône in seven days. An animated map.

Transcript
March, fifty-eight BC. News reaches Rome from the north.
The Helvetii burn their own towns and villages and set out west, toward the Rhône.
Caesar’s provinces lie just beyond the river: Cisalpine Gaul, Illyria and Transalpine Gaul.
Caesar sets out at once. He rides day and night. A counter marks the days: from one to seven.
On the seventh day he is at the Rhône, where it flows out of the lake.