Complex sentence: Both cities refused to pay the fines Charles imposed on them while avoiding takeover; in the case of Bremen, 12,000 imperial soldiers under the command of Eric II, Duke of Calenberg unsuccessfully laid siege from January until May.
Split into simpler sentences: Both cities refused to pay the fines Charles imposed on them and avoided occupation by imperial troops. In the case of Bremen, 12,000 imperial soldiers under the command of Eric II, Duke of Calenberg unsuccessfully laid siege from January until May.