Were underwater torpedo tubes on cruisers and battleships ever used successfully?
Short answerNo deliberate successful use is identified, although attempts appear to have been made and an example is not ruled out.
NotesThe question contrasts possible combat value with the flooding risk created by an underwater opening in a large warship's hull. Crews appear to have attempted to use these tubes, but no clear case of a deliberate success is identified. That failure of recollection is not treated as proof that no example exists. The distinction matters when assessing the weapon's doubtful operational record: an unremembered case is different from a disproved one.