Attila crossed the Rhine with an army estimated at 200,000 men, devastating Gallic cities including Metz, Reims, and Troyes. He nearly took Orléans before the combined Roman-Visigoth relief force arrived under General Aetius.
The only defeat of Attila's career. Roman general Aetius, allied with Visigoth King Theodoric I, halted the Hunnic advance in a catastrophic clash near Châlons. Theodoric died in the battle; both sides suffered enormous losses. Attila withdrew to the Hungarian plains — bloodied but unbroken.