Having shattered the reinforcing Imperial forces at Wittenweier, on 18 August, 1638 Bernhard encircled impregnable Breisach and prepared to starve its garrison out.
The Emperor desperately attempted to relieve the siege. Bernhard was easily able to turn back these spasmodic and ill-coordinated attacks. Through the autumn of 1638 the fortress starved.
Finally on 17 December, 1638 Breisach’s Governor von Rheinach capitulated. He was granted honorable terms.
The lenient terms were nearly revoked when Bernhard discovered that some of his men held prisoner in the fortress had been driven by shortness of provision to cannibalize their dead comrades.