Operation Gratitude

'Gratitude', which is otherwise known as the South China Sea Raid, was a US naval undertaking by Admiral William F. Halsey’s US 3rd Fleet (10/20 January 1945).

The raid was undertaken to support the liberation of Luzon in the Philippine islands group, and had as its primary targets Japanese warships, supply convoys and aircraft throughout the region.

After it had completed a series of attacks on airfields and shipping on and around Formosa and Luzon, the 3rd Fleet entered the South China Sea during the night of 9/10 January. Aircraft flying from its aircraft carriers attacked Japanese shipping off French Indo-China on 12 January, sinking 44 vessels. The fleet then sailed to the north and attacked Formosa again on 15 January. Additional raids were made on Hong Kong, Canton and Hainan during the course of the following day. The 3rd Fleet departed the South China Sea on 20 January and, after making further attacks on Formosa and the Ryukyu islands group, returned to its base on 25 January.

In overall terms, the 3rd Fleet’s operations in the South China Sea were highly successful. The US forces destroyed many Japanese ships and aircraft, while losing relatively few of their own aircraft, and it generally agreed that the destruction of cargo vessels and oil tankers was the most significant result of the raid as these losses contributed to closing a supply route which was vital to the Japanese war effort. Subsequent attacks by Allied aircraft and warships forced the Japanese to cease sending ships into the South China Sea after March 1945.

During 1941 and the early part of 1942, Japan had conquered or established de facto rule over almost the entire South China Sea region, whose control was vital to the Japanese economy and war effort, as it was the conduit through which essential supplies of oil and other natural resources passed from occupied Malaya, Borneo and the Dutch East Indies. The situation in French Indo-China was particularly complex. After a short military confrontation in September 1940 the colonial government, which was loyal to the Vichy French collaborationist régime, allowed the Japanese to use ports and airfields in northern part of the colony. In July 1941 the Japanese occupied southern Indo-China and established airfields as well as an important naval base at Cam Ranh Bay. The French authorities were permitted to remain as a puppet government. After the liberation of France in 1944, the colonial government sought to make contact with the new Free French government in Paris, and began preparations to stage an uprising against the Japanese. The Japanese also developed plans in 1944 for the forcible disarmament of the French forces and formally take control of Indo-China, and their intelligence services rapidly learned of the French authorities' intentions.

As the war turned against Japan, convoys of ships passing through the South China Sea frequently came under attack from Allied submarines and, by as time late in 1944, aircraft. These attacks were guided by information gained from signals intelligence and long-range air patrols, supplemented by reports from coast watchers along the Chinese coast and other observers in Asian ports. Major General Claire L. Chennault’s US 14th Army Air Force, which was based in China, regularly delivered attacks on Japanese shipping in the South China Sea. The 14th AAF also made periodic attacks on Japanese-held ports in southern China and military installations in Indo-China. However, the Allied clandestine services undertook few activities in Indo-China until the second quarter of 1945.

While its losses of oil tankers and freighters were increasingly heavy, the Japanese continued to instruct ships to make the passage through the South China Sea. In an attempt to limit losses, convoys and individual ships took routes well away from the established sea lanes, or sailed close to the shore and steamed only by night.

The USA began its liberation of the Philippine islands group on 20 October 1944, with the 'King II' landing on Leyte island in the central part of the Philippine archipelago. After a base had been established on Leyte, US forces landed on Mindoro island on 15 December in 'Love III', whose object was to secure airfields that could be used to attack Japanese shipping in the South China Sea and support the largest element of the liberation of the Philippine islands group, namely the 'Mike I' landing at Lingayen Gulf in the north-western part of Luzon island scheduled for 9 January 1945. The Imperial Japanese navy had suffered very heavy losses in its 'Sho' attempt to attack the Allied fleet during the Battle of Leyte Gulf in October 1944: combined with its catastrophic losses during the 'A' naval counter-offensive culminating in the Battle of the Philippine Sea in June 1944, this left it unable to conduct further major battles. However, it remained capable of raiding Allied positions.

Late in 1944, Halsey sought to conduct a raid into the South China Sea and led the development of plans for such an operation. On 21 November he asked Admiral Chester W. Nimitz, commander-in-chief of the US Pacific Fleet, for authorisation to begin the attack, but this was refused.

In December 1944, senior officers of the US Navy became concerned that the Imperial Japanese navy might attempt to cut the supply line to the planned beach-head at Lingayen Gulf. On 26 December a Japanese naval force operating from Cam Ranh Bay shelled the Allied beach-head on Mindoro, but inflicted no damage. One of the Japanese destroyers involved in this operation was sunk, and all of the remaining ships were damaged by Allied air and naval attacks before returning to Cam Ranh Bay.

As further Japanese raids were expected, senior US Navy officers believed that it was necessary to destroy the Imperial Japanese navy’s remaining mobile forces, which were thought to be split between Cam Ranh Bay and the Inland Sea of Japan. At this time the Inland Sea was beyond the range of the USAAF’s heavy bombers, meaning that an attack into the South China Sea was the only viable option for striking the Imperial Japanese navy. The US Navy’s intelligence service believed that the Japanese force based at Cam Ranh Bay was built around the two 'Ise' class battleships. Halsey and Nimitz discussed the proposed South China Sea raid once more during a meeting held around Christmas 1944 at the US Navy anchorage which had been established at Ulithi atoll in the Caroline islands group, and on 28 December Nimitz authorised Halsey to launch the attack once his fleet was no longer needed to directly support the Lingayen Gulf landings and 'if major Japanese fleet units were sighted' in the area. Halsey issued the pre-prepared plans for the operation to his subordinates on the same day. The undertaking’s goals were to attack the Imperial Japanese fleet and shipping. In addition, the Americans believed that the presence of a powerful naval force in the South China Sea would discourage any further Imperial Japanese naval operations in the area. While the 14th AAF was directed to attack Japanese shipping and airfields at Hong Kong in support of the invasion of Luzon, it was not informed of the plans for the 3rd Fleet to enter the South China Sea. The 14th AAF was also not briefed on the 3rd Fleet’s operations during the South China Sea raid, and no attempts were made to co-ordinate the two forces' operations during this period.

The 'Gratitude' plan for the raid specified that the 3rd Fleet would enter the South China Sea via the Luzon Strait before proceeding to the south-west. Warplanes of the fleet’s aircraft carriers were to attack Japanese positions on Formosa, and provide support for the landings at Lingayen Gulf on 9 January. Three submarines of Vice Admiral Thomas C. Kincaid’s 7th Fleet were to deploy into the South China Sea to rescue the aircrew of any US aircraft which were forced to ditch. This plan made it necessary for the 3rd Fleet to operate near many Japanese airfields, from which attacks could be mounted against the ships. Allied intelligence estimated that the Japanese had some 300 aircraft on Formosa, about 500 in southern China and northern Indo-China, another 170 in southern Indo-China, Burma and Thailand, and 280 in the Dutch East Indies. While most of these were Imperial Japanese army air force machines, which were less effective against warships than Imperial Japanese navy air force aircraft, there was a risk that kamikaze tactics would be employed. In addition, weather conditions were expected to be hazardous as the South China Sea is frequently affected by typhoons during January.

As of January 1945, the 3rd Fleet was built round the Fast Carrier Task Force, which was the main US Navy strike force in the Pacific Ocean theatre. Control of this force alternated at regular intervals between the 3rd and 5th Fleets, commanded by Halsey and Admiral Raymond A. Spruance respectively, with its designation also changing from Task Force 38 to Task Force 58. As TF38, this was commanded by Vice Admiral John S. McCain. In January 1945 TF38 was organised into three fast carrier task groups and a night carrier group. The fast carrier groups were Task Group 38.1 with four aircraft carriers, two battleships, six cruisers and 25 destroyers; Task Group 38.2 with four carriers, three battleships, five cruisers and 24 destroyers; and Task Group 38.3, which comprised four carriers, three battleships, five cruisers and 17 destroyers. The night carrier group, Task Group 38.5, had two carriers and six destroyers, and operated with Task Group 38.2 during the day. These four carrier groups embarked a total of about 900 aircraft. The other major element of the fleet was a logistics force designated Task Group 30.8, which comprised a varying number of tankers and ammunition ships, several escort carriers carrying replacement aircraft for TF38, and many escorting destroyers. In addition, the fleet was assigned an anti-submarine force designated Task Group 30.7, which comprised an escort carrier and three destroyer escorts and typically operated in support of Task Group 30.8.

Despite US concerns, the Imperial Japanese navy was not readying itself for any attack on the Allied supply lines, and Cam Ranh Bay was not a major fleet base. As of 1 January 1945, both the 'Ise' class battleships and the small number of other Japanese warships in the region were stationed in or near Singapore, and only escort vessels operated from Cam Ranh Bay. While large numbers of aircraft were based in Japanese-held territories bordering the South China Sea in January 1945, there were only a relatively few trained pilots available to fly them. At this time the Imperial General Headquarters was considering a major offensive against the supply line to Lingayen Gulf, but on 20 January it decided to concentrate Japan’s defensive efforts on the area around the home islands and undertake only delaying actions elsewhere.As a result, the Japanese forces in the region of the South China Sea at the time of 'Gratitude' were focused on preparing to resist future Allied attacks. The Japanese believed that US forces could possibly make a landing in Indo-China once the liberation of the Philippine islands group had been completed, and were also concerned about possible attacks on the area by the British-led South-East Asia Command. In an effort to create better co-ordination of the Japanese forces in the South-East Asia region, in January 1945 all Imperial Japanese army and navy units were placed under the overall control of the Southern Expeditionary Army Group, which was commanded by Field Marshal Count Hisaichi Terauchi from his headquarters in Singapore.

Despite these preparations, the Japanese remained unable to counter powerful attacks against shipping in the South China Sea. While the navy’s convoy escort forces had been expanded during 1944, they remained wholly inadequate. The most common escort vessel was the Kaibokan type of destroyer escort or frigate, but this was vulnerable to air attack as a result of its low speed and weak anti-aircraft armament.The Imperial Japanese navy also assigned few fighter aircraft to protect convoys in the South China Sea and, as a result of the almost traditional inter-service rivalry which badly hindered the Japanese war effort, rejected an offer from the Imperial Japanese army to provide additional fighters for this purpose just before the 3rd Fleet’s attacks on French Indo-China.

The 3rd Fleet departed Ulithi on 30 December 1944. On 3 and 4 January its aircraft carriers struck Japanese airfields on Formosa, Okinawa and nearby islands in an attempt to prevent their use for attacks on the Allied forces at Lingayen Gulf. In addition, its attack aircraft targeted Japanese shipping round Formosa, sinking at least three merchant vessels and damaging four frigates. Acting on a request from General Douglas MacArthur, commander-in-chief of the South-West Pacific Area, the fleet struck airfields on Luzon on 6 and 7 January. At about this time Kinkaid, commander of the 7th Fleet responsible for the Lingayen Gulf landings, asked Halsey to operate to the west of Luzon to provide air cover during the initial period of the invasion. Halsey believed it would be inappropriate for his force to operate in such a passive role, and instead ordered further attacks on the Japanese airfields in the southern part of Formosa which posed the greatest threat to Kinkaid’s command. These attacks were delivered on 9 January. During the morning of this day, Nimitz released the 3rd Fleet from directly covering the Lingayen Gulf area, and authorised it to enter the South China Sea. Once all of his attack aircraft had landed during the afternoon, Halsey issued orders to execute the planned attack into the South China Sea, and in the course of the 3rd Fleet’s operations between 3 and 9 January it destroyed more than 150 Japanese aircraft, but lost 86 of its own, including 46 in accidents.

During the night of 9/10 January the main body of the 3rd Fleet, including TG30.7, sailed through the Bashi Channel in the northern part of the Luzon Strait. TG30.8 was reduced to six fast tankers, two escort carriers and escorting warships, and reached the South China Sea via the Balintang Channel off the northern coast of Luzon. Neither force was detected by the Japanese, although night-fighters operating from the light carrier Independence intercepted and shot down three Japanese transport aircraft flying from Luzon to Formosa. The fleet also received a report that a large Japanese convoy of around 100 ships was sailing along the southern coast of China towards Formosa during the night of 9/10 January, but Halsey decided not to tackle it as doing so would disclose that his force was in the South China Sea and possibly prompt the Imperial Japanese navy to withdraw its battleships from the area.

While it was planned to refuel the fleet’s destroyers on 10 January, this was frustrated by bad weather. Instead, the destroyers were refuelled during 11 January as the fleet proceeded to the south-west. Once the destroyers had been refuelled, the 3rd Fleet was reorganised for combat. Two heavy cruisers and five destroyers were transferred from TG38.1 to TG38.2. It was planned that the latter, commanded by Rear Admiral Gerald F. Bogan, was to launch attacks on Cam Ranh Bay from its three large fleet carriers and single light carrier during the morning of 12 January. The task group’s two battleships, accompanied by destroyers and cruisers, would then bombard the area and finish off ships which had been damaged in the air attacks. The choice of targets was informed by intelligence passed on to the Allies by two networks of agents in Indo-China. The Third Fleet remained undetected by the Japanese on 10 and 11 January.

TG38.2 began its approach to Cam Ranh Bay at 14.00 on 11 January, and was followed by TG38.1 and TG38.3, which launched fighter aircraft to provide a combat air patrol over the fleet. TG30.8 remained in the central part of the South China Sea. Before the break of day on 12 January, TG38.5 launched aircraft to search for Japanese ships in the Cam Ranh Bay area. The crews of these aircraft signalled the location of Japanese ships by radio, and conducted an intensive search for the two 'Ise' class battleships and any other capital ships. When none was located, it was believed that the warships had been hidden from view by camouflage, and it took several months for the US Navy to learn that they had not been in the area. By 06.00 on 12 January, TG38.2 was within 50 miles (80 km) of Cam Ranh Bay, and its carriers and those of the other two task groups began launching their first attacks of the day at 07.31, about half an hour before sunrise. The Japanese had still not detected the 3rd Fleet’s approach, and were therefore unprepared for an attack.

The US airmen achieved considerable success against Japanese convoys. Two waves of aircraft from TG38.3 attacked a convoy of 10 ships escorted by the seven warships of the 101st Flotilla near Qui Nhơn in central Indo-China and sank four fully loaded oil tankers, three freighters, the light cruiser Kashii and three small escort vessels. Another convoy was located and struck near Cape Padaran in the southern part of Indo-China, resulting in the loss of a tanker, two destroyer escorts and a patrol boat. A convoy comprising seven vessels was also attacked near Cape St Jacques in the southern part of Indo-China, leading to the sinking or beaching of two freighters, three tankers, three destroyer escorts and one landing craft.

US aircraft also struck Japanese shipping in the area of Saigon, sinking two freighters and one tanker in Saigon, and another tanker off the coast. The disarmed French light cruiser Lamotte-Picquet was mistakenly attacked and sunk in Saigon, despite flying the French flag. Many other ships were damaged in the Saigon area, including five freighters, two tankers, three landing craft, two to four destroyer escorts, one minesweeper and one patrol boat. Several of these ships were beached and were destroyed by a storm later in the month. Other 3rd Fleet aircraft were used to maintain a combat air patrol over the area between Tourane in the central part of Indo-China and Saigon, and attacked airfields, docks and oil storage facilities. The railway station at Nha Trang and a bridge on the line between Saigon and Bien Hoa were also damaged. The surface attack group, which had separated from TG38.2 at 06.40 and comprised two battleships, two heavy cruisers, three light cruisers and 12 destroyers, located no Japanese ships.

Thus the attacks of 12 January were highly successful: 46 Japanese ships had been sunk, including 33 merchant vessels with a combined tonnage of 142,285 tons; 12 of these merchant vessels were tankers. The 13 warships which had been sunk were the light cruiser Kashii, two destroyers, seven coast-defence vessels (CD-17, CD-19, CD-23, CD-35, CD-43, CD-51 and Chiburi), the patrol boat No. 103, the minelayer Otowa Maru and the military transport vessel T-140. While few Japanese aircraft were operational, the US airmen shot down 15 aircraft and destroyed 20 floatplanes at Cam Ranh Bay and another 77 aircraft on various airfields. The 3rd Fleet lost 23 aircraft. The French colonial government refused to hand over to the Japanese the downed US airmen its forces captured, and provided them with escorts to the frontier with Chinese. Civilians also rescued US airmen and helped them to escape. As a result, almost all of the US Navy aircrew from aircraft shot down over Indo-China eventually returned to the USA via China.

At 19.31 on 12 January, the 3rd Fleet reversed course and sailed to the north-east for a meeting with TG30.8. This course was maintained during the following day in order to evade a typhoon and Japanese search aircraft. Heavy seas made fuelling difficult, though all of the destroyers were eventually refuelled on 13 January. On that day, Admiral Ernest J. King, the Chief of Naval Operations, directed the 3rd Fleet to remain 'in a strategic position to intercept enemy forces approaching the Lingayen Gulf area from either the north or the south'. In forwarding this order to Halsey, Nimitz authorised him to attack the Hong Kong area if more worthwhile targets could not be located.

On 14 January the US warships continued to refuel in spite of adverse weather. All of the major warships were eventually refuelled to at least 60% of their fuel capacity. This consumed most of TG 30.8’s supplies, and the task group later separated from the fleet to rendezvous with relief tankers near Mindoro. After fuelling had been completed, the 3rd Fleet sailed to the north for an attack on Formosa. Weather conditions continued to be bad, and at o3.00 on 15 January McCain recommended to Halsey that the planned attacks be cancelled and the fleet sail to the south. Even so, Halsey decided to continue to the north and execute the attack. In addition, he ordered the launch of aircraft during 15 January for reconnaissances of Amoy, Hainan island, Hong Kong, the Pescadores islands group and Swatow in search of the 'Ise' class battleships. The newly designated night carrier Enterprise launched search aircraft at 04.00 that morning.

Attacks were launched from the carriers beginning at 07.30 on 15 January, and at this time the 3rd Fleet was about 255 miles (410 km) to the east-south-east of Hong Kong and 170 miles (270 km) to the south-west of Formosa. Some 10 fighter sweeps were despatched to Formosa, and another six to airfields on the Chinese coast. In addition, eight raids were launched against shipping in the Takao and Toshien regions of Formosa. While many ships were located, these attacks were largely frustrated by bad weather and heavy anti-aircraft fire. The destroyer Hatakaze and the 'No. 1' class landing ship T-14 were sunk at Takao City and one tanker was damaged and forced aground. Several of the attacks were diverted to Mako in the Pescadores islands group, where weather conditions were better, and these aircraft sank the destroyer Tsuga. A weather station and radio facilities on Pratas island were also attacked by aircraft from Enterprise. The US pilots claimed to have shot down 16 Japanese aircraft and destroyed another 18 on the ground during the day,while the US Navy lost 12 aircraft in combat and accidents. At 16.44 the carriers changed course to reach the position from which Hong Kong and other locations in southern China were to be attacked on the next day.

The British colony of Hong Kong had been captured by the Japanese in December 1941, and became a significant naval and logistics base. USAAF units based in China attacked the Hong Kong area from October 1942. Most of these raids involved a small number of aircraft, and typically targeted Japanese cargo ships which had been reported by Chinese guerrillas, but by January 1945 the city was being regularly raided by the USAAF.

The launch of the 3rd Fleet’s first raids on 16 January began 07.32. The day’s operations were focused on Hong Kong, which was struck by 138 aircraft during the morning and a further 158 in the afternoon. The raiders sank five large tankers and an Imperial Japanese navy oiler, and damaged several other ships. The tankers formed part of the Hi-87 convoy which had been diverted from its passage to the south in an attempt to avoid the 3rd Fleet. Kai Tak airport was also attacked and badly damaged, and all the aircraft on the ground were destroyed. Widespread damage was also inflicted on the Kowloon and Taikoo docks. Several less important targets, including the dockyard in Aberdeen and trains on the railway linking Kowloon and Canton, were struck by pilots who had been authorised to engage targets of opportunity. The village of Hung Hom, which was located near the Kowloon docks, was heavily bombed and hundreds of civilians were killed or wounded. The internment camp at Stanley was also hit by a bomb that killed 14 of the Allied civilians imprisoned there.The 14th AAF’s 118th Tactical Reconnaissance Squadron conducted an attack on shipping at Hong Kong on 16 January which was not co-ordinated with the US Navy’s raids. These were the largest air attacks conducted on Hong Kong during World War II.

The Japanese garrison of Hong Kong strongly resisted the raid, using particularly effective anti-aircraft tactics which the Americans had not previously encountered. A US Navy report described the gunfire the aircraft faced as having been 'intense to unbelievable'. The Grumman TBF Avenger torpedo bombers despatched against Hong Kong suffered particularly heavy losses as their low-level attack runs proved highly vulnerable to anti-aircraft fire, and as the Avengers' torpedoes had been set to run too deep these attacks achieved little.

The Portuguese colony of Macau, across the Pearl river estuary from Hong Kong, was also struck. While Portugal was neutral, the colony’s government had been forced to accept the presence of Japanese 'advisers' since 1943 and had traded weapons for food supplies. The raid’s primary target was a stockpile of aviation fuel at the Macau naval aviation base, which the Allies had learned from local agents was to be sold to the Japanese. The fort of Dona Maria II was also attacked, possibly to destroy a radio station located within or near it, and some damage was inflicted on civilian areas and the city’s harbour. Two soldiers and several civilians were killed. Macau’s garrison lacked any effective anti-aircraft weapons, and did not fire on the US aircraft.

Other attacks were made on locations in the southern part of China on 16 January. Strikes were made on Canton, and two raids and two fighter sweeps were flown against locations in Hainan. In addition, fighters struck at the airfields along the Chinese coast between the Leizhou peninsula in the west and Swatow in the east, but encountered few Japanese aircraft.

The US losses on 16 January were 22 aircraft shot down in combat and 27 lost in accidents. The Japanese claimed to have downed 10 aircraft over Hong Kong alone.The US pilots reported that they had destroyed 13 Japanese aircraft. At least four American airmen were taken prisoner after being shot down near Hong Kong, and a further seven evaded capture and eventually reached Allied-held regions of China. One of the US prisoners was later murdered by a lethal injection at the Ofuna prisoner of war camp in Japan.

After completing its attacks on 16 January, the 3rd Fleet turned to the south to refuel. Because weather conditions were particularly bad on the following day, fuelling was not completed, and the weather worsened further on 18 January, making fuelling operations impossible. During this period Japanese propaganda radio broadcasts claimed that the fleet had been 'bottled up', and would be destroyed when it tried to leave the South China Sea. As his meteorologists expected the adverse weather to continue into 19 January, Halsey decided to depart the South China Sea via the Surigao Strait in the central part of the Philippine islands group rather than sail to the north around Luzon. When Nimitz learned of this, however, he requested that the 3rd Fleet use the Luzon Strait, although Halsey was given discretion to make the final decision on his force’s route. Nimitz’s reasoning was that if the fleet sailed through the central part of the Philippine islands group its departure would be reported by Japanese forces on bypassed islands, possibly leading to an Imperial Japanese navy attempt to raid the Allied supply lines. In addition, a northerly passage would leave the 3rd Fleet better situated for its tasks, which included another attack on Formosa and a reconnaissance of the Ryukyu islands group.

Halsey opted to follow Nimitz’s request. The 3rd Fleet completed fuelling on 19 January, and proceeded to the north toward the Balintang Channel; TG30.8 separated from the main body, however, and subsequently passed through the Surigao Strait. During 20 January the 3rd Fleet steamed to the east through the Balintang Channel, with a division of destroyers patrolling well ahead of the carrier task groups. Many Japanese aircraft were detected by radar during this period, and 15 of these, which were evacuating men of the Imperial Japanese army air force from Luzon were shot down. No attack was made against the US force, and the 3rd Fleet exited the Balintang Channel at 22.00.

After departing the South China Sea, the 3rd Fleet proceeded to its next tasks. Its aircraft attacked airfields and harbours on Formosa on 21 January, and sank 10 merchant ships at Takao. A Japanese aeroplane struck the light carrier Langley with two small bombs, and the fleet carrier Ticonderoga was badly damaged by two kamikaze aircraft. The destroyer Maddox was also struck by a kamikaze aeroplane, but suffered little damage. In addition, McCain’s flagship Hancock suffered considerable damage when a bomb fell from a TBF Avenger which had just landed and exploded on her flight deck. Hancock and Ticonderoga were detached from the fleet, and steamed to Ulithi for repairs. On 22 January the remaining carriers struck at targets on the Ryukyu islands group. The primary objective of this effort was to gain photographic coverage of Okinawa to help plan the 'Iceberg' invasion of the island, and airfields and shipping were also attacked. Once this task had been completed, the fleet turned to the south for Ulithi during the evening of 22 January, and arrived there on 25 January. On the following day, Halsey passed command to Spruance, and the 3rd Fleet thereupon became the 5th Fleet.

'Gratitude' was seen as a major US success. During its operations in the South China Sea between 10 and 20 January, the 3rd Fleet had steamed some 3,800 miles (6115 km) without suffering heavy casualties or a serious mishap. Nimitz later stated that 'the sortie into the South China Sea was well-conceived and brilliantly executed' and praised the planning for the fleet’s logistical support, but regretted that Japanese capital ships had not been located and attacked.

The Japanese high command believed that the 'Gratitude' raid had been undertaken in preparation for an invasion of southern China. Thus five more infantry divisions were assigned to the defence of this area, but three of these were released for other operations in March 1945 after the US 'Detachment' invasion of Iwo Jima was interpreted as evidence that the the area of Hong Kong and Canton would be bypassed rather than attacked.

The South China Sea raid also contributed to the Japanese decision to take full control of Indo-China. The commander of the Imperial Japanese army forces in Indo-China, Lieutenant General Yuitsu Tsuchihashi, believed that the raid was the precursor an Allied invasion of the area. In reality, President Franklin D. Roosevelt had decided that the USA would not commit itself to any liberation of Indo-China, and there were no plans for any such effort. As part of attempts to prepare for an Allied invasion and pre-empt any French uprising, on 26 February the Japanese authorised the military command in Indo-China to implement the takeover plans as soon as the necessary preparations had been completed. This occurred on 9 March, with the Japanese forces attacking and rapidly defeating most of the French garrisons. The Japanese then installed Emperor Bao Dai to rule over the puppet Empire of Vietnam, Kingdom of Cambodia and Kingdom of Laos.

The Portuguese government lodged a protest over the US Navy’s violation of Macau’s neutrality shortly after the raid on 16 January, and the US government apologised for the incident on 20 January. An official court of inquiry was held, and in 1950 the USA provided Portugal with a $20.3 million compensation payment for the damage caused to Macau’s harbour on 16 January and other accidental raids on 11 and 25 June 1945.

Allied air and naval attacks against Japanese shipping in the South China Sea were expanded during early 1945 as additional USAAF units moved into bases in the Philippine islands group. Land-based patrol aircraft and medium bombers operated over the sea from liberated areas of the Philippine islands group and the Dutch East Indies from February. While Allied submarines and these aircraft failed to prevent the escape of the 'Ise' class battleships when they departed Singapore for Japan in 'Kita' in the middle of February, the medium bombers were sinking large numbers of Japanese merchant ships by the end of the month. Medium and heavy bombers also raided Japanese-held ports across the South China Sea area. As a result of the air and submarine attacks, the Japanese ceased sending ships through the South China Sea in April 1945.