This was the Japanese plan within ‘Sho’ for the strategic defence of Formosa and the Ryukyu islands group (summer 1944).
Now known as Taiwan, Formosa is a large island with an area of 13,974 sq miles (36193 km²), and is located off the south-east coast of the Chinese mainland. The island had been part of the Imperial Japanese empire since the 1st Sino-Japanese War of 1896 and, with the exception of sporadic but long-lasting resistance by indigenous tribesmen in the deep interior, was quickly pacified: The Treaty of Shimonoseki, which ended the war and transferred sovereignty over Formosa to Japan, included an unusual clause giving the Chinese on the island two years to leave rather that accept Japanese rule: this was intended specifically to eliminate potential troublemakers. The initial wave of Japanese army administrators and civilian 'carpetbaggers' was soon replaced by the administration of Governor General Gentaro Kodama and his brilliant civil administrator, Shinpei Goto.
During the next decade, Formosa was radically transformed into a laboratory in which Japanese skills at modernisation, based on Japan’s own modernisation in the Meiji era, could be displayed. Goto took the time to understand local customs, and adapted local institutions such as the pao-chia village militia to help maintain order. Careful thought went into planning the development of a local sugar industry, which soon became self-sufficient. However, the law giving the governor general authority to legislate for the colony was repeatedly attacked as infringing on the legislative monopoly of the Japanese Diet.
By 1941, Formosa had many military bases and some industrial development. It supplied Japan with most of its sugar as well as small quantities of bauxite.
The island’s terrain is generally mountainous except for the western coastal plain, where most of the population lives, and the climate is subtropical. The most important cities were Taipeh on the north coast and and Takao on the south-west coast. The island was ruled by a governor general, who was often a vice admiral or lieutenant general, and who was personally recommended to the emperor by the prime minister on the advice of the genro (an unoffical but influential body of retired statesmen) and the army leadership. On the outbreak of the Pacific War of World War II, the governor general was Admiral Kiyoshi Hasegawa Kiyoshi, who was succeeded on 30 August 1944 by General Rikichi Ando.
The native Formosans are an Austronesian people predating the first Chinese settlements in the 17th century. The Japanese initially confined the native Formosans to large reserves in the deep interior, where they were fenced off and with a special permit required for anyone to enter or leave the reserves. To a time as late as 1931, almost 50% of the colonial police force was used to supervise the native Formosans, and much of the policing took the form of encouraging the native Formosans to lay down they weapons and became farmers. This effort was generally successful, and the area of land under native Formosan cultivation more than doubling and the rice yield more than tripling.
The native Formosans numbered about 140,000 persons in 1929 and were relatively loyal to the Japanese, and in some of the Pacific War’s early campaigns Formosan civilian volunteers proved themselves to be excellent carriers and scouts. Later, native Formosan recruits were grouped into companies under Japanese officers trained in guerrilla warfare. The Allies first encountered these units at Leyte when the 1st Raiding Company carried out a suicidal attack from aircraft deliberately crash landed on Burauen airfield in the Philippine islands group.
Some 1.36 million Formosans volunteered for military service in 1942/1943, often under pressure from recruiters, but a mere 3,505 of these were inducted into regular Japanese army units. Formosans were not subject to conscription until January 1945.
By late 1944 the island had 15 army airfields, 11 navy air stations, and two seaplane bases.
Ready for implementation at the end of August 1944, the 'Sho 2' plan was based on the defence of the large island of Formosa by General Rikichi Ando’s Formosa Army (Lieutenant General Yasuyuki Okamoto’s 10th Division, Lieutenant General Sadanao Ishimoto’s 50th Division and Lieutenant General Kisaburo Nakashima’s 66th Division) and Lieutenant General Kenji Yamamoto’s 8th Air Division, while the defence of the Ryukyu islands group was entrusted to Lieutenant General Mitsuru Ushijima’s 32nd Army (Lieutenant General Mamoro Hara’s 9th Division, Lieutenant General Tatsumi Amamiya’s 24th Division, Lieutenant General Senichi Kushibuchi’s 28th Division and Lieutenant General Yoshio Hongo’s 62nd Division).
On Formosa the 10th Division was then posted to General Tomoyuki Yamashita’s 14th Area Army in the Philippine islands group during November and replaced by Lieutenant General Hidezo Hitomi’s 12th Division from Manchukuo.
Admiral Ernest J. King, the US Chief of Naval Operations, favoured an assault on Formosa rather than Luzon in the Philippine islands group as the ultimate objective of the Pacific counter-offensive, but his thinking was opposed by the commander of the South-West Pacific Area, General Douglas MacArthur and, somewhat surprisingly, by the commander of the Pacific Ocean Areas and the Pacific Fleet, Admiral Chester W. Nimitz. MacArthur’s staff estimated that the conquest of Formosa would require nine divisions and more service troops than would be available until after the defeat of Germany. The decision to invade Luzon rather than Formosa was then made by President Franklin D. Roosevelt, who was persuaded in part by MacArthur’s argument that it was a political imperative to liberate the Commonwealth of the Philippines. The Joint Chiefs-of-Staff Committee formalised this decision on 3 October 1944, following the recommendations of the San Francisco conference of 29 September/1 October 1944.
Formosa was not assaulted by the Allies, and the Ryukyu islands group became the target of ‘Iceberg’.
However, between 10 and 14 October 1944, Admiral William F. Halsey’s US 3rd Fleet undertook a series of carrierborne air attacks against Okinawa and Formosa with the objective of interdicting the possible flow of Japanese air reinforcements to the Philippine islands group, where the 'King II' invasion of Leyte island was scheduled to start on 20 October. The attacks on Formosa began on 11 October, and caught Admiral Soemu Toyoda, the commander-in-chief of the Combined Fleet, on Formosa, so Rear Admiral Ryunosake Kusaka, his chief-of-staff, immediately ordered preliminary preparations to execute 'Sho', the Japanese Navy’s contingency plan for an Allied move against the Japanese inner defence perimeter. Kusaka also ordered the air groups from the remaining Japanese carriers to deploy to Formosa. As a result, these air groups were savaged and their carriers rendered toothless for the forthcoming 'Sho 1' (the Battle of Leyte Gulf).
The Air Battle of Formosa within 'Sho 2' took place between 10 and 20 October off the east coasts of the Ryukyu islands group, Formosa and Luzon, and involved the Imperial Japanese naval air force and the approaching Task Force 38 of the US 3rd Fleet. The battle was wholly one-sided inasmuch as the US forces completely dominated the air war as a result of the current total superiority in aircraft numbers, aircraft capabilities, weapons and crew training. The Japanese air strength in the region was battle exhausted, but in an effort to boost morale and to conceal the defeat, the Imperial Japanese headquarters claimed to have sunk 45 Allied ships, including 11 aircraft carriers and four battleships.
The Japanese order of battle included 1,251 naval fighters and bombers. Vice Admiral Kimpei Teraoka’s 1st Air Fleet, based in Manila in the Philippine islands group, had 144 aircraft, Vice Admiral Shigeru Fukudome’s 2nd Air Fleet based in Takao on Taiwan had 358 aircraft, Vice Admiral Shunichi Kira’s 3rd Air Fleet had 275 aircraft, Vice Admiral Jisaburo Ozawa’s 3rd Fleet based at Kisarazu in the Chiba prefecture of Honshu island in the Japanese home islands, had 237 aircraft, and Vice Admiral Eiji Goto’s 12th Air Fleet had 237 aircraft. On the other side of the aerial front line, the 3rd Fleet had 17 fleet and light aircraft carriers, six battleships, four heavy cruisers, 10 light cruisers and 58 destroyers. Task Group 38.1 had the fleet carriers Wasp and Hornet and the light carriers Cabot, Cowpens and Monterey; TG38.2 has the fleet carriers Bunker Hill, Hancock and Intrepid and the light carrier Independence; TG38.3 had the fleet carriers Essex and Lexington, and the light carriers Langley and Princeton; and TG38.4 had the fleet carriers Enterprise and Franklin, and the light carriers Belleau Wood and San Jacinto.
The 3rd Fleet started carrier-launched raids against Formosa on 11 October, and the Japanese response was to send waves of aircraft against the US carriers. By the following day the Japanese air strength on the island of Formosa had been all but destroyed. In the fighting, the light cruiser Houston was damaged by a Japanese torpedo, while the carrier Hancock, light cruiser Reno and two destroyers all incurred some form of damage. Over three days the Japanese lost between 550 and 600 aircraft, which was almost their entire air strength in the area, as well as about 40 merchant vessels. US aircraft losses totalled 89 machines.
However, the Japanese managed to fly eight torpedo bombers past the US fleet defences at sunset on 13 October and badly damaged the heavy cruiser Canberra, flooding both engine rooms. Rather than scuttle the ship, Halsey decided to have the crippled cruiser towed to safety while conducting an additional unscheduled strike against Formosa. That night, another Japanese dusk raid put a torpedo into light cruiser Houston, flooding all her engineering spaces. Again, Halsey chose to have the crippled ship towed to safety rather than be scuttled. The two ships were joined by escorts and were organised into 'CripDiv1' (Cripple Division 1) for their long tow to repair at Ulithi atoll. The Japanese committed several attacks against the cripples, inflicting very light damage from a bomb hit on the carrier Franklin and scoring another torpedo hit on Houston. This latter almost finished the cruiser, but excellent damage control saved the ship.
As a result of Japanese radio broadcasts claiming a great naval victory off Formosa, Halsey now decided to use the cripple ships as bait to draw out the main strength of the Japanese Navy, which could then be ambushed and destroyed. Thus 'CripDiv1' became 'BaitDiv1'. The Japanese despatched only a small force of cruisers and destroyers of the 5th Fleet to mop up the 'shattered' US fleet, however, and its commander, Vice Admiral Kiyohide Shima, sensed a trap and withdrew his ships before they could be ambushed.