By 976, Henry II had returned to Bavaria. Whether Otto II released him from prison or he escaped is not known for certain. Upon his return, Henry openly rebelled against Otto II, claiming rulership over the Empire for himself. Henry II mobilized the Saxon nobility against Otto II. In particular, Henry II had strong connections to Margrave Gunther of Merseburg, Count Egbert the One-Eyed, and Dietrich I of Wettin, who were all displeased with Otto II's lack of adherence to Saxon tradition. In response to the rebellion, Otto II stripped Henry II of his duchy and had him excommunicated. Otto II then marched his army south to Bavaria and laid siege to Regensburg, Henry II's stronghold. Otto II's army eventually broke through the city's defenses, forcing Henry II to flee to Bohemia.