Following the Swedish defeat at the Battle of Nördlingen in 1634, Bernhard's mercenary army had come under the pay of France.

Early in February 1638, having been prodded by the French government, Bernhard advanced his army of 6,000 men and 14 guns[3] to the Rhine in order to find a crossing.

In order to prevent this, the Imperialists, under the Italian mercenary Count Federico Savelli and German general Johann von Werth, moved through the Black Forest to attack Bernhard's army and relieve the town.

However, by the time Savelli appeared with the main body of his force only half of Bernhard's army had made it to the north bank.

Like a revolving door both armies swung round giving Savelli the chance to capture the ferry and cut off Bernhard from his troops on the south bank.

Bernhard had his artillery fire three times into the Imperial ranks before a final charge broke the Imperialist army.