The Battle of the Lisaine, also known as the Battle of Héricourt was fought from 15 January to 17 January 1871 between Prussian and French forces. The French were led by Charles Denis Bourbaki, and were attempting to relieve the Siege of Belfort. The Prussians prepared multiple corps, about 52,000 men, to halt the French advance of about 152,000 men. The Prussian corps had their outer posts overran quite swiftly but the Prussians forced back and counterattacked the French forces, breaking the morale of French troops and leaving them to either die or retreat. In the end their efforts failed, and they were forced to flee into Switzerland where they were all interned soon after.