How long could Bismarck, Prinz Eugen, and the German battlecruisers operate in the Atlantic before exhausting their supply ships?
Short answerAbout a month if they avoided sustained high-speed maneuvering and remained near economical cruising speed.
NotesFuel and supply endurance, not gun power, sets the approximate one-month window. That estimate assumes economical movement, yet a continuous British hunt would repeatedly force the squadron to maneuver, disperse, or increase speed. Its practical freedom would therefore shrink even before the supply network was physically exhausted.