Legend of the Galactic Heroes – S02 E20 : Admiral Yang's Ark Fleet

On Iserlohn Yang decides to abandon the fortress. Yang realizes that the fortress no longer has strategic value as a choke point defense after the Imperial fleet has broken through Phezzan space. Furthermore, the Fortress would be able to hold out till the end of the war, but would probably be forced back into Empire territory in the event of a peace treaty. Yang's fleet prepares bombs and another surprise on Iserlohn and abandons the fortress of all staff and civilians. January 9, 799 S.C. / 490 Reuenthal has retaken Iserlohn fortess.