In French hands since 1644 - with Breisach, it was then their only bridgehead on the east bank of the River Rhine and so Vauban had fortified it.

This made it a constant threat to the Holy Roman Empire's west flank and at the outbreak of the Franco-Dutch War it became the jumping off point for several French incursions into the Palatinate and Neckar area.

The garrisons of its outlying towns of Kißlau, Schwetzingen and Bruchsal were destroyed in spring 1676 and the Empire decided to lay siege to the fortress itself.

Charles V, Duke of Lorraine began the siege with a 40,000 strong imperial force on 23 June.

Only 1,500 French troops survived but these were allowed to march out with full military honours.