The battle off Formosa (12-16 October 1944) was an air battle between Japanese naval aircraft based on Formosa and the aircraft of the US 3rd Fleet that ended with an overwhelming American victory that crippled Japanese naval air power just days before the battle of Leyte Gulf (23-26 October 1944).
In the summer of 1944 the Japanese were aware that the Americans would probably soon invade the Philippines or Formosa, and put in place a series of plans that they hoped would result in a 'decisive battle' in which the big battleships of the Japanese navy would finally earn their keep. Sho-Go, or Operation Victory, was split into Sho-1 for the defence of the Philippines and Sho-2 for the defence of Formosa. Most of the naval forces involved in these plans were under the command of Admiral Toyoda, commander of the Combined Fleet. When the American air attacks began he was visiting Formosa, and witnessed some of the fighting. Formosa was defended by the Sixth Base Air Force, commanded by Vice Admiral Shigeru Fukudome.
The forces that were allocated to Sho-Go were effectively withdrawn from combat in the build-up to the battle, to avoid wearing down their strength before the decisive battle. This also helped convince the Americans that Japanese air power was even weaker than it actually was.
The battle was triggered by a series of heavy American attacks that were designed to reduce Japanese air power before the landings at Leyte Gulf in the Philippines. On 10 October Admiral Halsey's 3rd Fleet began a new wave of attacks with a massive strike on Okinawa, part of the Japanese Home Islands (although some way to the south of the main islands). After unleashing his four carrier groups on Okinawa, Halsey then moved south to attack Formosa.
Admiral Toyoda believed that such heavy air attacks had to mark the start of an invasion, and so he issued the orders to begin Sho-1 and Sho-2. When the Americans send the first of three waves of attacks against Formosa on 12 October they were faced with an unexpectedly heavy level of opposition. Two hundred and thirty Japanese aircraft were sent into the attack, outnumbering the incoming American fighters by about 3 to 2. Unfortunately for the Japanese most of their pilots were very inexperienced, and a shortage of fuel meant that they were barely trained. One third of the Japanese fighters were lost in the battle against the first wave of Americans and most of the rest in the second wave. The third wave was thus almost entirely unopposed.
On 13 October the American air attacks met with little opposition, and inflicted heavy damage on the Japanese airfields. That evening the Japanese finally managed to strike back. A force of just over 30 night bombers was sent against the American fleet. The carrier Franklin was hit by bombs but only suffered minor damage. The cruiser Canberra, a rare example of an US warship named after a foreign city, was hit by a torpedo below the armour belt (commemorating HMAS Canberra, lost at the battle of Savo Island in 1942). She was stopped in the water and was in a very vulnerable position, close to enemy territory and over one thousand miles from a safe base. Halsey decided to try and tow the Canberra out of the danger zone.
In order to try and divert attention away from the Canberra, Halsey decided to launch a third series of strikes against Formosa on 14 October. Once again the Americans dominated in the air, but once again the Japanese were able to get through to the fleet, and the light cruiser Houston was hit near the engine room by a torpedo. By the end of the day both the Canberra and the Houston was being towed toward safety.
Those inexperienced Japanese pilots who did survive the battle reported a series of dramatic successes, and their accounts were believed. On 16 October the Japanese announced that they had sunk eleven aircraft carriers, two battleships, three cruisers and one destroyer or light cruiser. They did admit to the loss of 312 aircraft but claimed to have shot down 112 American aircraft in return.
On 15 October the Japanese thus believed that they had inflicted a major defeat on the Americans, and the existence of 'Cripple Division 1', the force attempting to get Canberra and Houston to safety seemed to confirm this. Toyoda ordered Fukudome to go after what he believed were the fleeing remnants of the 3rd Fleet. Another 600 naval aircraft were transferred from Japan to Formosa, including the aircraft that were allocated to the remaining aircraft carriers. Three strikes were launched on 15 October. Two failed to find the Americans and the third was repelled, again with heavy losses.
The final Japanese attacks came on 16 October. This time 107 aircraft found the American ships but only three managed to get past the fighter screen. One of these aircraft managed to get a second torpedo into the Houston, but the badly damaged cruiser remained afloat and with the Canberra reached safety.
The only failure on the American part came when Halsey attempted to use 'Cripple Division 1' to lure part of the Japanese fleet out of the safety of the Inland Sea. At first Toyoda fell for this, and ordered Admiral Shima to bring his II Striking Force out to take part in what he believed was the pursuit of a defeated enemy. Shima's fleet almost fell into the trap, but it was withdrawn after a clash with American aircraft and survived to take part in the Battle of Leyte Gulf.
The battle off Formosa had a major impact on the course of the battle of Leyte Gulf. The Japanese had managed to gather together a large number of naval aircraft and at least partly trained crews to take part in Sho-Go, but over 600 of them were lost off Formosa. This meant that the Japanese carriers had no air groups and could only be used as a decoy, and the rest of the Japanese fleet lacked any air cover, making it much easier for the Americans to find them and make repeated heavy attacks on them.