 The operation began on 12 October , when Moltke , Bayern , and the Königs began firing on the Russian shore batteries at Tagga Bay . Simultaneously , the Kaisers engaged the batteries on the Sworbe peninsula ; the objective was to secure the channel between Moon and Dagö islands , which would block the only escape route of the Russian ships in the gulf . Both Grosser Kurfürst and Bayern struck mines while maneuvering into their bombardment positions ; damage to the former was minimal , and the ship remained in action . However , Bayern was severely damaged , and temporary repairs proved ineffective . The ship had to be withdrawn to Kiel for repairs ; the return trip took 19 days . 
