The final Japanese mass naval sortie (Operation Ten-Go)

Based on: https://www.alternatehistory.com/fo...operation-heaven-number-1-ten-ichi-go.463770/

POD 1: The battleships Ise and Hyuga, the cruiser Oyodo and their escorting destroyers are loaded totally with tons of crude fuel oil in anticipation of future usage in another naval sortie. They depart from Singapore on 11 February 1945 (a day later than reality) and reach Kure 10 days later as in reality. In addition, orders given from the crew of the warships to load the Japanese tankers departing Singapore for Japan loaded with crude oil purely with crude oil (other ships, including tankers carrying only gasoline in such convoys, carry roughly the same cargoes as in reality) and to get any seaworthy Japanese cruisers left in Singapore to reach Japan carrying only crude fuel oil by March 1945.
 
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POD 2: Ultra intercepts on 20 February 1945 reveal the imminent departure of Ashigara and Haguro by 25 February 1945 with escorting destroyers Nokaze, Kamikaze and Amatsukaze totally laden with crude oil (it will occur starting 1 March, excluding the still-damaged Amatsukaze, Nokaze having temporarily avoided its actual fate). The sortie (named Operation Kita 2) will also see all the aforementioned ships (excluding the still-damaged Amatsukaze) reach Kure on 11 March 1945. The diversion of submarines and planes to hunt the warships will save a few Japanese tankers (Nichiyoku, Eisho, Amato, Palembang, Ryoei, Tatekawa, Yaei No. 1, Yamakuni, Hosen, 6th Takasago, 21st Nanshin and not diverted southwards Nanshin No. 30 Marus, together with naval tanker Hario) sunk in late February and early March 1945 from being sunk, giving Japan about 50,000 tons more fuel and the ability to use more ships for Operation Ten Go. All the fuel needed for Operation Ten Go reached Kure to be pumped into the Japanese navy ships involved in the operation by 2 April 1945.

On 19 March 1945, bombers from the USAAF and US carrier planes bomb and leave aircraft carriers Ryuho and Kaiyo unrepairable and severely damaged at Kure (butterflies resulting in less damage inflicted on battleships, cruisers, destroyers and Unryu-class carriers at Kure and Oyodo not being damaged in the raid). In exchange, the USS Franklin is very severely damaged and sent to New York City for long repairs with 724 dead.
 
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If Ashigara and Haguro make it, they can join TEN-GO, along with the CL Sakawa (Yahagi's sister), Oyodo, Tone, and the aforementioned destroyers. Forget the carriers: what good are they with no trained air groups?

One thing about TEN-GO: the closest thing in the IJN to a mutiny came when the skippers were being briefed. RADM Keizo Komura (ComDesron 2), CAPT Tamechi Hara (Yahagi), along with ComDesDiv 41 and two of his captains (two Akizuki-class DDs) wanted to go off on a raid into the shipping lanes between Okinawa and the Marianas. Arguments in Yamato's Flag Country were heated, but the orders stood. Now, having additional cruisers and the fuel to operate them? This might mean Komura's ships do go off on their raid-maybe with Sakawa and one or two additional destroyers.

Additional ships won't change the final outcome, though: Mitscher's TF 58 put more aircraft (381) over the Yamato group in the largest war-at-sea strike in history; more than Nagumo's Kido Butai did at Pearl Harbor (353). And that's not allowing for the first wave returning, being turned around, and going out to finish off any cripples.

It would distract attention from Desron 2 as it goes off on its convoy raid, though.
 
The Sortie

On 6 April 1945, the Imperial Japanese Navy will depart Kure with its active and stationed at Kure major warships for the last time in an operation to sink American ships off Okinawa and then beach the ships involved on Okinawa for fuel and shore bombardment purposes before blowing them up and using its crews to fight on land with army troops (all ships involved are totally assigned to Second Fleet under Seiichi Ito). The fleet, consisting of Yamato, Haruna, 2 Ise class battleships, Oyodo, both Haguro class cruisers in Japan, 2 Unryu class carriers with aircraft compliments reduced, aircraft carrier Hosho with no planes, cruiser Tone, 2 Yahagi class cruisers, kaiten carriers Kitakami and Namikaze, 1 each of (non-kaiten) destroyers from the Namikaze, Kamikaze, Hibiki, Asashio and Yugumo classes, 3 Kagero class destroyers, 5 Akizuki class destroyers and 16 Matsu class destroyers will sail to their destruction after being spotted by USS Threadfin.

On 7 April 1945, the Second Fleet will be spotted by planes from USS Essex at 8:30 a.m. and the last devastating fight for the Imperial Japanese Navy begins. The planes of 8 American carriers in the area are launched at 10:00 a.m. that day. Two hours later, the Unryu class carriers, with only 70 planes on both carriers combined, are only able to sink the USS Bataan by the time all their planes are lost to kamikaze crashes and enemy fire, the last Japanese carrier strike of WW2. At 1:00 p.m., the planes of the American carriers, having found the Japanese carrier task force and being diverted to the carriers, started hitting the Amagi and Katsuragi with bombs and torpedoes, resulting in the Japanese carriers being sunk by 4:30 p.m.. Simultaneously, the destroyer Asashimo, staggering behind due to engine damage, is sunk with all hands by USS San Jacinto's planes at around 1:00 p.m. that day. The last strike of the US carrier planes for the day will sink the Hosho, its obsolete design, poor damage control and an overwhelming usage of planes against Hosho leaving it unable to survive the impact of 3 torpedo hits that it capsized at 7:15 p.m. on 7 April 1945.
 
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It might be harder for the U.S. pilots. With all those ships the anti aircraft fire would be a lot worse.
 
The Sortie

On 6 April 1945, the Imperial Japanese Navy will depart Kure with its active and stationed at Kure major warships for the last time in an operation to sink American ships off Okinawa and then beach the ships involved on Okinawa for fuel and shore bombardment purposes before blowing them up and using its crews to fight on land with army troops (all ships involved are totally assigned to Second Fleet under Seiichi Ito). The fleet, consisting of Yamato, Haruna, 2 Ise class battleships, Oyodo, both Haguro class cruisers in Japan, 2 Unryu class carriers with aircraft compliments reduced, aircraft carrier Hosho with no planes, cruiser Tone, 2 Yahagi class cruisers, kaiten carriers Kitakami and Namikaze, 1 each of (non-kaiten) destroyers from the Namikaze, Kamikaze, Hibiki, Asashio and Yugumo classes, 3 Kagero class destroyers, 5 Akizuki class destroyers and 16 Matsu class destroyers will sail to their destruction after being spotted by USS Threadfin.

On 7 April 1945, the Second Fleet will be spotted by planes from USS Essex at 8:30 a.m. and the last devastating fight for the Imperial Japanese Navy begins. The planes of 8 American carriers in the area are launched at 10:00 a.m. that day. Two hours later, the Unryu class carriers, with only 70 planes on both carriers combined, are only able to sink the USS Bataan by the time all their planes are lost to kamikaze crashes and enemy fire, the last Japanese carrier strike of WW2. At 1:00 p.m., the planes of the American carriers, having found the Japanese carrier task force and being diverted to the carriers, started hitting the Amagi and Katsuragi with bombs and torpedoes, resulting in the Japanese carriers being sunk by 4:30 p.m.. Simultaneously, the destroyer Asashimo, staggering behind due to engine damage, is sunk with all hands by USS San Jacinto's planes. The last strike of the

If only 70 Japanese planes, with poorly trained crews, were able to get through to sink a carrier, I'd be surprised. US AA is absolutely *murderous* in 1945, thanks to proximity shells, and the 'Big Blue Blanket' anti-kamikaze CAP would have a field day with barely-trained pilots, who would be outnumbered by about 3:1 by better pilots in better planes.
 
If only 70 Japanese planes, with poorly trained crews, were able to get through to sink a carrier, I'd be surprised. US AA is absolutely *murderous* in 1945, thanks to proximity shells, and the 'Big Blue Blanket' anti-kamikaze CAP would have a field day with barely-trained pilots, who would be outnumbered by about 3:1 by better pilots in better planes.
They overwhelmed and sank the light carrier USS Bataan by having the few surviving planes go kamikaze and attack the Bataan overwhelmingly. That would be their only success in the battle and the Japanese would lose all 70 planes in the strike alone.
 
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The Naval Battle of Okinawa

After the carrier battle of 7 April, it is time for the Japanese battleships to engage their American counterparts. The Japanese battleship engagement will start at 10:00 a.m. on the morning of 8 April 1945, with shells from USS Tennessee hitting Yamato. Yamato will move forward to badly damage and sink the Tennessee, but will be sunk by 3:00 p.m., having been engaged by Tennessee, Nevada, Idaho, New York, New Mexico and West Virginia and having sank only the Tennessee by 2:00 p.m.. The Haruna will entangle with the Arkansas and Colorado and will suffer fatal damage after a combat of 2 hours, sinking at 12:50 p.m. and having been crippled and sinking in its last hour. Calls for the help of Ise and Hyuga will see Ise crippled and sunk by carrier planes by 3:00 p.m. and Hyuga engaged and sunk by 7:00 p.m., the timely intervention of the Colorado playing a role in Hyuga's destruction for medium damage to Colorado and fatal torpedo damage to Arkansas launched from 6 Matsu-class destroyers, all of them being destroyed in the battle in exchange for USS Morrison. In addition, the Kaiten launched by the Kaiten carriers will be evaded by USS Texas (which will receive the only kaiten hit of the battle), USS Maryland, USS Tuscaloosa and their destroyers, which will proceed to destroy the kaiten and sink both Kitakami and Namikaze (in addition to Nokaze and Kamikaze of "Destroyer Division No. 1") by 6:00 p.m., the delay being due to evasive movements to avoid the kaiten. After the battle, USS Texas will be detached and reach Saipan on 18 April 1945 due to survivable kaiten damage.

The cruiser and destroyer battle will be more even sided, but will see the sinking of all Japanese cruisers and destroyers involved in escorting Yamato (Tone, Oyodo, Haguro, Ashigara, Yahagi, Hibiki, Yukikaze, Isokaze, Hamakaze, Kasumi, Suzutsuki, Fuyutsuki, Hanazuki) due to orders by Seiichi Ito to continue the battle to the last cruiser and the last destroyer. In exchange, the US will lose the heavy cruisers Pensacola and Salt Lake City to torpedoes and gunfire and the destroyers Mannert L. Abele, Porterfield, Cassin Young, Bryant, Heywood L. Richards and Bennion. All Japanese ships involved in the surface battle on 8 April will be sunk by 10:00 p.m. that day. USS Arkansas will sink due to torpedo damage early on 9 April 1945.

Having sank the Hyuga, the American carrier planes will sink the Sakawa and 1 Matsu-class destroyer by 5:40 p.m. and cripple another Matsu-class destroyer which will later be scuttled at night. On 9 April, the remaining American carrier planes will sink the remaining destroyers of the Ten Go fleet, costing the Japanese another 6 destroyers. Total losses for the Japanese Navy as a result of 3 days of combat in Ten-Go will comprise of 4 battleships, 3 aircraft carriers, 70 carrier-based planes, 3 heavy cruisers, 4 light cruisers and 30 destroyers in total, not counting 100 land-based (and lost in combat or as kamikaze) aircraft. The Americans lost 60 carrier-based planes (30 with USS Bataan), 1 light carrier, 2 battleships, 2 heavy cruisers and 7 destroyers in the battle as a whole. The Japanese navy as a whole is now crippled by fuel and ship shortages and the very few remaining survivors will be unseaworthy for service due to battle damage and fuel shortages. To make things worse, all tankers sailing with Convoy HI-88J have been sunk the previous week, ensuring that there will be no additional fuel bound for Japan. Operation Ten Go will be a massive disaster for the Japanese surface fleet.
 
Aftermath of the Ten Go disaster

In the aftermath of the Ten Go disaster and the sinking of Isuzu on 7 April 1945 without having the Japanese Ten Go ships reach the Okinawa beaches, an escort carrier, a destroyer escort or the invasion fleet, the Japanese Navy is confined to only 2 irreparable aircraft carriers left in port, several incomplete aircraft carriers left incomplete, the battleship Nagato, the light cruiser Kashima, several armoured cruisers, 2 heavy cruisers left in Singapore crippled and irreparable (they will be sunk by midget submarine raids on 30 July 1945, salvaged and permanently scuttled in 1946 off the Straits of Malacca), the cruiser Aoba and 18 destroyers not counting newly completed replacements (with 5 Tachibana-class destroyers sunk between 25 June 1945 and 30 July 1945 and Amatsukaze sunk by British destroyers on 16 May 1945 off the Andamans). On 30 July 1945, a mine will sink the last Akizuki-class destroyer left, Natsazuki.

US air raids on 18 July 1945 on Yokosuka will fail to sink the Nagato (although it proceeds like its actual counterpart), but on 24 July 1945, US carrier air raids will sink the irreparable Aoba, 3 armoured cruisers, the light carrier Ryuho, the escort carrier Kaiyo and 2 incomplete Unryu-class carriers at Kure. On 28 July, the sunken wrecks at Kure and the Kure drydocks will be further damaged by carrier-launched air raids, along with destroyer Shii fatally. In addition, on 24 July 1945, the British carrier force will sink escort carrier Shimane Maru and 2 escorts (the remaining Shimane Maru-class carriers being incomplete by war's end). Tokiwa will be sunk on 9 August 1945.

With Haguro , Nokaze, Kamikaze and Ashigara sunk at Okinawa in Operation Ten Go and Nokaze's initial fate being butterflied, Amatsukaze will be sunk by British destroyers on 16 May 1945 (its destruction by US bomber planes in reality will be replaced by subchaser CH-9's destruction by the bomber planes), the sinking of torpedo boat Kiji on 8 June 1945 by HMS Trenchant and torpedo boat Kari will be sunk by USS Hawkbill on 18 July 1945. Japanese patrol boat losses will be the same as in reality, plus Patrol Boat No. 36's destruction on 20 July 1945 by USS Baya. USS Indianapolis will be sunk on 30 July 1945 as in reality. The sinking of USS Bataan will make it the only US fleet carrier sunk in 1945 and the last to be destroyed, although the US will lose 3 escort carriers that year (USS Sangamon on 4 May 1945 and 2 others as in reality) to kamikaze strikes and severe kamikaze damage will force USS Franklin, Bunker Hill and Enterprise out of the war for repairs.

By the Japanese surrender of 15 August 1945, to be signed on 2 September 1945 on USS Missouri, after the Soviet declaration of war on Japan and the nuking of Hiroshima and Nagasaki, only the light cruiser Kashima, 2 armoured cruisers (one decommissioned), 2 crippled and sunken heavy cruisers at Singapore, 2 aircraft carriers at Sasebo (incomplete and bombed Ibuki and Kasagi), the abandoned Nagato, several incomplete Shimane Maru class carriers, 2 destroyers converted into training ships and 16 completed destroyers (at least 3 irrepairable, including Harukaze) were able to constitute a decent Japanese Navy surface ship battle fleet. Except for 10 destroyers ceded to the WW2 Allies, the mined destroyer Kuri and Nagato's nuking at Operation Crossroads on 2 July 1946 (targets in the operation same as its otl counterpart and not returned to service after the operation excluding already destroyed Sakawa), all the above ships and the wrecks at Kure will be scrapped by August 1948. More reliance on USN ships for Japanese repatriation from ex-Japanese conquests to mainland Japan post-war. The Japanese will also be left with 81 Kaibokan surviving WW2 as well, with at least 4 irrepairable.
 
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If Ashigara and Haguro make it, they can join TEN-GO, along with the CL Sakawa (Yahagi's sister), Oyodo, Tone, and the aforementioned destroyers. Forget the carriers: what good are they with no trained air groups?
Could the carrier not be used for Ohka and have them launched from a carrier.
 
Kind of a little joke, but maybe not. At this stage in the war it might be better and easier if the USN just runs away until the IJN ships run out of fuel. Then just sink them or leave them to starve or surrender.
 
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