Wakatsuki sinks the USS Harder in June 1944

[ghappy1000]

World War II Sea War, Volume 13: New Guinea, Normandy and Saipan

In April, May and June 1944, there were three major areas of naval conflict: In New Guinea: United States (US) and Australian forces landed at Aitape and Hollandia, then at Arare, Wakde and Biak Island. In Europe: The battle for the control of the English Channel heated up. The German navy...

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Wakatsuki, after being attacked by the USS Harder, tried to depth charge USS Harder and sink it, but failed to sink it.

If Wakatsuki successfully depth charged and sank USS Harder on 6 June 1944, then, it means kaibokan CD-22 won't be sinking USS Harder on 24 August 1944. Also, it means that USS Harder would have sank only 2 Japanese destroyers instead of 4 Japanese destroyers (and one destroyer per destroyer sinking patrol instead of one Japanese destroyer per destroyer sinking patrol and three Japanese destroyers in the next destroyer sinking patrol), reducing to eliminating its reputation as the "destroyer killer" and as "hit them again Harder", especially since it will mean USS Harder's destruction by a destroyer instead of by a kaibokan.

As for the Japanese ships most likely saved by USS Harder's earlier demise, Hayanami will escort Japanese Navy ships and fight with Kurita during Philippine Sea and Leyte Gulf before being sunk on 27 October 1944, taking down USS Johnston 2 days before. It will share the fate of Fujinami in Japan's Destroyer Division 32.

As for Tanikaze, it will be able to deter USS Cavalla from attacking Shokaku during Philippine Sea, allowing Shokaku to survive Philippine Sea. Therefore, the Japanese can still use Shokaku for Cape Engano. Net effect is the linked thread below, but replace Taiho with Shokaku and any likelihood of Shokaku being nuked if it survived WW2 would be revenge for Pearl Harbor and general Japanese aircraft carrier testing for nuclear bomb survivability at Operation Crossroads. Otherwise, the Shokaku can still be sunk at Cape Engano or in bomber raids or by USS Redfish and Unryu shares the fate of Katsuragi in the scrapyard, or of Nagato in Japanese battleship testing for nuclear bomb survivability at Operation Crossroads. The Tanikaze likely shares the fate of Yukikaze in surviving WW2.

WI: The IJN Taiho survives

In the June 19 1944, the IJN Taiho, the newest aircraft carrier of the Imperial Japanese Navy, is struck by a torpedo from the submarine USS Albacore. Thanks to elevator pits placed below the waterline, a chain of events followed that resulted in Taiho blowing up in flames, with only around 500...

www.alternatehistory.com

As for the last 3 Japanese ships saved by the early demise of USS Harder, these will be the kaibokan Sado, Hiburi and Matsuwa. Even the mere absence of USS Harder means that the 3 kaibokan survive 22 August 1944 and are able to escort the tanker Niyo Maru together with Asakaze. On 23 August 1944, the Sado is torpedoed and sunk 1 day later than otl, but Asakaze will still be around and seaworthy enough to sink or chase away USS Haddo before USS Haddo sinks Asakaze.

Net effect even with minimal butterflies will be the saving of 2 destroyers (Tanikaze and Asakaze) and of 2 kaibokan (Hiburi and Matsuwa) for Japanese use in WW2, for their surrender to the Allies and for long term Allied use after WW2. No way the Shokaku will be in long term Allied use after WW2 because it will be sunk or scrapped before ownership and crew operating are surrendered for long term Allied use after WW2.

 

[mack8]

You can even get to a scenario where NO japanese carrier are sunk at the Marianas. Can the extra destroyers deter the attack on Taiho too? Or at least if we swap the hit on Taiho so it hits Shokaku instead, the Shokaku is much more likely to shrug it off and survive. There will still be the US air attacks the next day, but with Shokaku and Taiho there, they might attract more US planes and perhaps Hiyo is not torpedoed, so it survives. Shokaku and Taiho might be hit by couple of bombs each, but they will survive as well. As for torpedoes, they are much more likely to avoid a torpedo compared to the very slow Hiyo, so that one torpedo hit might be butterflied away.

Could also mean a few more planes and pilots than OTL survive the battle, that historically sank with Shokaku might survive.

It is true that Shokaku and Taiho might meet their end at Engano, but again their sacrifice might mean some of the other carriers might survive, maybe couple of CVL or the "lucky" Zuikaku.
Come to think of it, with more carriers available, perhaps the japanese won't commit the still training carrier groups to the Formosa air battle? So Ozawa could have 2 or even 3 times more planes at Engano. Not a battle winner, but who knows what effect they might have? Saving the Musashi somehow?

Can other US submarines with notable successes be butterflied this way? Such as the one that sank Shinano? Or maybe some of the ones that attacked Kurita at Leyte?

 

[Sekhmet_D]

As for Tanikaze, it will be able to deter USS Cavalla from attacking Shokaku during Philippine Sea, allowing Shokaku to survive Philippine Sea.

I doubt this. Japanese ASW capabilities were lousy; Cavalla practically sank Shokaku right under Urakaze's nose. If Urakaze failed to stop Cavalla, I see no reason why Tanikaze would succeed.