From: Near Portland, OR
It appears the discussion is about real world torpedo attacks. My next question is what does "most successful" mean? And are we talking about an overall raid with multiple waves, or a single attack? Success could mean tactical results achieved from the attack, or it could mean overall strategic success of the overall operation that stemmed from the torpedo attack.
If you're looking at strategic successes, the attack on the Bismarck wasn't tactically spectacular, but the one hit jammed the rudder allowing the British surface fleet to catch up and pummel the ship.
Another strategic success was a single Beaufort attack on the Gneisenau when she was at Brest. The British heavily reconned the port and attempted to bomb the ships there, but torpedoes attacks were not possible because of the heavy torpedo netting around the ships and the shallow part of the harbor where they were kept. British recon showed the Gneisenau outside the torpedo nets one day. She was in the process of being moved and was parked for a short time at a spot that could be torpedoed. A strike of Beauforts was launched, but encountered heavy fighter defenses. One Beaufort got through and put a torpedo in the Gneisenau, but was shot down on the way out. The Gneisenau was in dry dock for some time after that. She had just come out when the raid destroyed the dock.
Tactically the sinking of the Musashi was fairly poor. At that point in the war the USN bomber pilots had poor strike discipline and the strike was poorly coordinated. In a target rich environment like that, the strike bombers should initially aim to disable as many ships as possible. After the first or second wave, the Musashi was obviously in trouble and should have been ignored in favor of other targets, but the bombers kept focusing on her. Additionally the dive bombers wasted their bombs on the battleships where they couldn't punch through the deck armor. They would have been better suited to attacking cruisers.
Six months later when the USN attacked the Yamato, there was much better strike coordination and discipline. Some dive bombers did drop on the Yamato, but their mission was flak suppression rather than doing serious damage. They dropped general purpose bombs intended to take out flak guns above the armor and they were very effective. Fighters also went in ahead of the torpedo bombers with rockets to suppress flak. In that attack the torpedo bombers all aimed for one side of the ship which sank the ship a lot faster than the attacks on the Musashi which scored hits on both sides and effectively did counter flooding for the damage control crews.
The attacks on the Center Force at Leyte was only the second strike on major warships the USN had done since 1942. The crews had mostly forgotten what training they did have for that type of strike and discipline was poor. I believe the Intrepid's VTs did best in that strike because they had been drilled on strike tactics better than other units. However, they attacked Musashi too.
The 1945 USN strikes on the Japanese fleet in the home islands was very effective. I don't know how many torpedo planes were used there, but the strikes sank most of the surviving IJN fleet. They didn't have the fuel to sortie at that point, but it eliminated the fleet in being. You are guaranteed a sunk battleship won't be giving you any problems.
Depending on the criteria, you can disect historical torpedo attacks and come to all sorts of conclusions.
WitP AE - Test team lead, programmer