The War at Sea 1943
New technologies
The Allies and the Axis both bring new weapons and innovations to the war at sea in 1943. The Allies radically improve radar, developing the proximity shell which detonates in close range of attacking aircraft, millimeter band radar suitable for deployment aboard small craft, submarines and aircraft, improved centimetric band radars, and develop the combat information center for more effectively controlling air defense and antisubmarine warfare. They also develop the Leigh Light, a powerful airborne searchlight for maritime patrol aircraft, as well as the Hedgehog, a forward firing mortar that on detonates if it hits a submarine which reduces lost contact issues previously experienced when using depth charges and the resultant noise disrupting sonar tracking.
The Allies also have sent dozens of new American destroyer escorts, Canadian corvettes as well as over two dozen escort carriers, with more coming all the time. These new carriers, carrying Wildcat (Martlet) fighters and Avenger bombers serve as the core of escort groups for the most vital convoys, while support groups, built around older carriers like the Hermes and Eagle, are available to assist convoys under the heaviest attack.
In the air, the Allies have 15 American groups of Liberators, 6 of Canadian Liberators, as well as 20 RAF Coastal Command Liberator groups, while all three still operate groups of flying boats and other aircraft such as the Halifax and Wellington. Most of these are in the Atlantic, but they can be found in the Pacific and Indian Oceans as well. The Australians and New Zealanders as well as the Free French are also operating several groups of various maritime patrol aircraft, usually Catalina, Sunderland and Hudson maritime patrol aircraft. All of these aircraft are heavily armed for strafing attacks, carry a substantial load of depth charges or bombs and many also are armed with rockets and some even carry the new homing torpedoes.
Against this the Japanese have built more of submarines, but they have not markedly improved them while the Germans and Italians are using their same old models, but both are developing new ones that should see service in 1944. The Axis have however added more anti-aircraft guns and many now carry air search radar, while the Germans are also using the new homing torpedo. The new innovation for the Japanese is airborne radar in small quantities for night torpedo attack squadrons, first used in the Marshall Islands battle, while the Germans have added much the same capabilities as the British to the small number of aircraft they have devoted to maritime patrol missions. The Germans have developed a new weapon, the Fritz X guided bomb but have not used in combat before the Armistice occurs. The Americans and British are developing similar weapons.
The Tonnage War – Atlantic February – April 1943
When the Truce comes to an end, the Kriegsmarine as 500 type VII and 100 Type IX submarines, while the Italians have 10 submarines suitable for action in the Atlantic. They find themselves facing nearly 2,000 Allied escorts, thousands of aircraft, and the former Big Gap in the mid-Atlantic that was a problem in 1941 is long gone. The new escort groups with carrier support and the support groups available to reinforce big convoy battles results in devastating losses for the Uboat Wolf Packs, as even during night hours aircraft can show up at any time, and the determination to force convoys through instead of rerouting them brings the Germans to battle. The result is 200,000 tons of shipping lost in two months, along with 34 escort ships including the escort carrier USS Card, but 80 Uboats are sunk, twice that number are damaged, and the entire Italian force is wiped out.
Doenitz is already calling off the battle when the Armistice occurs, badly shaken at his losses and disturbed by how little result was gained at such a cost. A cost that includes his son.
Tonnage War – Pacific
The Japanese however are far less skilled in Anti-submarine warfare and indeed have barely started routine merchant shipping convoys when the Truce ends. They have also remained tied to the notion that submarines are there to support the battlefleet instead of using them as commerce raiders. The Americans on the other hand, along with small numbers of British, French and Dutch submarines have no such notions while Allied escorts are far more deadly to the larger and thus slower-diving Japanese boats (compared to German Type VII boats). The result is a painful lesson in modern naval warfare for the Japanese and the lesson that Mahan is not the only thinker who should be consulted about the war at sea. At the cost of 6 American, 1 Dutch and 1 British boat, the Allied submarines sink 1.5 million tons of Japanese shipping in the 11 months after the truce in 1943, and by the end of 1944 will sink another 2.1 million tons (although 8 American, 2 British and a Free French submarine will be lost as well). Among the losses are 150,000 tons of assault shipping, cutting in half the Japanese ability to make assault landings or for that matter, evacuate troops in a hurry, and several major warships are sunk along with the nearly 40 Japanese escort vessels lost between the end of the Truce and the end of 1944. This is not even counting the Japanese losses to other causes, such as air attack.
As of the end of the Truce the Japanese had 5.9 million tons of shipping and they build only 700,000 tons of shipping in the 23 months after the Truce. Imports begin to fall, and oil imports plunge especially as the Americans in particular focus on Japanese oil tankers, sinking nearly half the fleet in 23 months. Meanwhile more and more submarines are added to the Allied force, and the torpedo problems that plagued the US Navy in 1941 and 1942 are finally resolved completely by late 1943.
For Japan this is a far worse disaster than the loss of the Battle Line in the Marshall Islands. Now the very fabric of the economy is under assault and Japanese wartime production begins to unravel.
The Fast Carrier Raids
After the end of the Marshalls Campaign the 3rd Fleet is given to Admiral Towers, who has been all but begging for a sea command since the start of the war and who was the head of the US Navy aviation component when the war began. Nimitz is send to the Pacific in May after Admiral King suffers a stroke that sends him home (authors note: a stroke he had historically in 1947 but he is under more pressure in this timeline). Admiral Kimmel finally gets to leave his job as American representative on the Combined Joint Chiefs and takes over the command of the US Atlantic Fleet. Nimitz keeps Spruance as his chief of staff, but orders him to focus on planning of invasions planned for 1944 when more amphibious shipping is available. He also orders Lee to take a rest and makes Admiral Kincaid commander of the surface forces (and thus second in command) while making Admiral Soc McMorris, who won the Battle of Kula Gulf in the Solomons, the chief of staff to Powers.
3rd Fleet July – October 1943
Carriers: Essex, Hornet (II), Saratoga (II), Intrepid, Bunker Hill, (Oriskany, Cabot joining in September and October), Light carriers: Independence, Princeton, Belleau Wood, Cowpens, Monterrey, battleships Iowa, New Jersey, Washington, North Carolina, Massachusetts (South Dakota, Alabama rejoining the fleet in September and October), 5 anti-aircraft cruisers, 5 heavy cruisers, 5 light cruisers, 20 destroyers (10 more destroyers join the fleet when the additional carriers do). Supporting this is a fleet train with dozens of support ships along with several escort carriers and 30 more destroyers.
The Great Raids
The Fast Carriers leave Pearl Harbor with 10 carriers and their escorts as well as 600 aircraft and head into the Pacific. They hit Truk first, which is already under steady attack by the 8th Air Force B24s operating out of new bases in the Marshall Islands. Next is Wake Island, which is worked over thoroughly followed by the Marshall Islands and then the Caroline Islands where a convoy of 8 destroyers and 12 transports carrying troops and artillery en route to reinforce the fortress at Truk is discovered and only 3 of the escorts manage to escape in the Battle of the Caroline Islands (85,000 tons of shipping are sunk and over 13,000 Japanese are killed in this one sided massacre). The Carrier based Hellcats also shoot down dozens of Japanese Army and Navy aircraft in the battle as the Japanese attempt to protect the convoy in vain. That the USS Seawolf sinks two of the surviving destroyers (resulting in another 2,000 Japanese deaths) is just the icing on the cake.
Battle of Lae / Nassau Bay
After a brief bit of refitting at Kwajalain in early September, the 3rd Fleet heads south, working over Rabual and then hammering Japanese airfields at Lae, Wewak and Hollandia, and providing distant cover to Allied landings at Lae and Nassau Bay in October when the Australian 8th Infantry Division and US 7th Infantry Division are landed by Admiral Wright, who has as fire support the battleships New Mexico, Idaho, Nevada, Tennessee, and California plus numerous cruisers and destroyers from the US, British, Australian, New Zealand and Free French Navy. This operation is also the air assault combat debut for the US Army, which drops the 11th Airborne Division on the Japanese airfield and then flies in the bulk of the 32nd Infantry Division as well. General Short, commander of the US 6th Army, is killed in this battle in a plane crash somewhere in the New Guinea highlands, and General Patch is hurriedly given command of the battle which results in the destruction of 8,000 Japanese troops at the cost of 4,000 Australian and American casualties. In support of the landing, the US 41st Infantry Division is landed at Cape Gloucester, the southern tip of New Britain, and this clears the way for an advance up the New Guinea northern coast.
Bypassing the enemy
After the heavy casualties in the Marshall Islands and the Aleutian campaign which shows that bypassing the enemy pays big dividends, Eisenhower and Nimitz agree that reducing Truk and Rabaul does not require a direct assault. The shortage of amphibious assault shipping is also a factor, and so is the desire for a speedy advance into the Japanese Empire while the Imperial Navy is still recovering from the defeat in the Marshall Islands. Truk and Rabaul will be bypassed and left to wither on the vine. Eisenhower will advance up the New Guinea coast, with Wewak and Hollandia and the Admiralty Islands as his objectives for the next six months, while assembling shipping and troops for the landing at Dili, Ambon and Sorong to follow. This should put him in position to establish airbases for the 10th Air Force to strike at Japanese oil production, which both theater commanders have directives from the Combined Chiefs to acquire as soon as possible. This also puts Eisenhower in position to move on Borneo and the Philippines after that. Nimitz will be moving on Saipan, Guam, Yap and Ulithi in the summer of 1944, while also supporting the North Pacific offensive which is to take place at the same time against Petropavlovsk in Kamchatka.
The Anglo-Indians are now under the direction of Field Marshall Alexander (newly promoted), commander of the South Asian Theater, and Admiral Somerville is flown to the meeting at Pearl Harbor to meet with Nimitz and Eisenhower. The British plan is for a landing in the Andaman Islands in January 1944, with an invasion of Sumatra at Medan timed for June 1944. This combined pressure on four major fronts will overstretch the Japanese and place bases within range of their principal oil supplies. This also puts the British in position to invade Malaya and places them in the Japanese rear as the Indian Army moves into Burma and then Siam.