This was the US seizure of a sizeable lodgement on Mindoro island in the central part of the Japanese-occupied Philippine islands group (15/21 December 1944).
Mindoro is located to the south of Luzon in the Philippine islands group, and is the seventh largest island of the archipelago, 110 miles (177 km) long and 58 miles (93 km) wide with an area of 4,082 sq miles (10572 km²). The island is dominated by a forested mountain range reaching to a height of 8,481 ft (2585 m) at Mt Halcón in the north, with scrub-covered coastal plains to the east and south-west. The chief city and port was San Jose on the south-western corner of the island, where Ilin island shelters a small anchorage. However, the island was poorly developed in 1941 and remained so under Japanese occupation, with only a rudimentary road network. The only paved road extended along the east coast. and there was a short railway running to the north-west from San Jose. The total population in the World War II period was in the order of 117,000 persons.
General Douglas MacArthur’s South-West Pacific Area command had at first proposed that after a swift conquest of Leyte island, to the south-east of Mindoro, the US forces should make their next effort directly against Luzon, the main land mass of the Philippine islands group and the core area of General Tomoyuki Yamashita’s 250,000-man 14th Area Army. But the slow pace imposed on the US advance on Leyte by the unexpectedly strong Japanese resistance required that the Luzon invasion had to be postponed from December 1944 to January 1945, which meant that tactical air support could not be furnished by Major General Ennis C. Whitehead’s 5th AAF within Lieutenant General George C. Kenney’s Far East Air Force, whose airfields would be waterlogged at that time.
Unwilling to rely exclusively on the US Navy’s considerable force of escort carriers to provide the level of tactical air support which would be needed in a major land campaign, MacArthur decided to improvise a landing on Mindoro, already considered for invasion within the ‘Musketeer’ ('Reno V') scheme, so that better-sited airfields could be built on Luzon’s doorstep within easy range of Lingayen Gulf and the Manila area. The island also fell within the scope of the US desire to recover the whole of the Philippine islands group from Japanese occupation.
Mindoro was MacArthur’s wholly logical choice as the location for the new advanced bases which were required for the staging and support of the formations tasked with the subsequent operations in the Philippine islands group, namely Lieutenant General Walter C. Krueger’s 6th Army and Lieutenant General Robert L. Eichelberger’s 8th Army.
Lying just to the south of the main body of Luzon, Mindoro is generally mountainous, with a few narrow plains along its coast. The combination of daily rain and high humidity made the island a fertile breeding area for the mosquitoes and other lifeforms responsible for malaria and other tropical diseases, but the Japanese defences on the island were minimal: the defenders comprised only about 1,000 Japanese army and navy personnel as well as 200 marooned sailors. The main Japanese strength was just two provisional infantry companies detached from Lieutenant General Yoshitake Tsuda’s 105th Division on Luzon, and a company-sized diversionary (commando) unit, and overall command was exercised by the headquarters of Lieutenant General Shizuo Yokoyama’s 8th Division on Luzon.
The planning of ‘Love III’ to take the island proved itself a difficult task. Amphibious landings in the north-east of Mindoro offered the best tactical possibilities, but would clearly be vulnerable to attack by whatever was left of Japanese air power on Luzon, so this region was discarded for the launch of 'Love III'. The town of San Jose near Mangarin Bay, which was Mindoro’s best deep-water port, thus became the location selected by the US planners.
It was on 13 October that MacArthur issued orders for the invasion of Mindoro at a scheduled date of 5 December with the object of taking areas for the construction of airfields from which cover could be provided for the 'Mike I' landings at Lingayen Gulf on Luzon, planned for implementation two weeks later. Delays in constructing airfields on Leyte meant that the US forces were unable to wrest complete control of the air over the Philippine islands group from the Japanese, however, and in combination with significant shipping losses from kamikaze attacks this compelled MacArthur to postpone the Mindoro invasion to 15 December and the Luzon invasion to 9 January 1945. Six escort carriers were also assigned to the Mindoro invasion force to provide additional air cover. Even so, the operation was daring but somewhat risky, for it represented a leap of 260 miles (420 km) into restricted waters surrounded by enemy airfields.
The detailed planning and implementation of ‘Love III’ was assigned to the 6th Army, which allocated the task to Major General Roscoe B. Woodruff’s 24th Division, whose assault effort, under the immediate command of Brigadier General William C. Dunckel, assistant divisional commander, was to be made by the Western Visayan Task Force comprising the 11,878 combat troops of the 19th Infantry, one battalion of the 21st Infantry and Lieutenant Colonel George M. Jones’s separate 503rd Parachute Regimental Combat Team, increased to a total strength of 17,780 men by the addition of an anti-aircraft artillery group, service troops, four airfield construction battalions, and an airfield construction squadron of the Royal Australian Air Force. The USAAF involvement totalled another 9,578 men.
The primary threat to the amphibious assault vessels and their supporting warships came from land-based kamikaze aircraft, which the Japanese had started to use in the final stages of the US ‘King II’ operation to take Leyte, and perfected by December 1944.
The invasion was undertaken by Rear Admiral Arthur D. Struble’s Western Visayan Attack Force, which was divided into a Mindoro Attack Group of eight converted destroyer transports, 30 tank landing ships, 12 medium landing ships, 31 infantry landing craft, 17 minesweepers and 14 other small craft, escorted by the light cruiser Nashville and 12 destroyers; Rear Admiral Russell S. Berkey’s Close Covering Group with one heavy cruiser, two light cruisers and seven destroyers; a Motor Torpedo Boat Group of 23 PT-boats; and a Slow Tow Convoy with three destroyers, two destroyer escorts, six fleet tugs, one fuel tanker and two tank landing craft. Distant cover was provided by Rear Admiral Theodore D. Ruddock’s Heavy Cover and Carrier Group with six escort carriers (Natoma Bay and Rear Admiral Felix B. Stump’s Carrier Division 24 comprising Manila Bay, Marcus Island, Kadashan Bay, Savo Island and Ommaney Bay each carrying 24 fighters and nine torpedo bombers, battleships West Virginia, Colorado and New Mexico, light cruisers Denver, Montpelier and Columbia, and 18 destroyers of Destroyer Squadrons 22 and 54 operating in the Sibuyan Sea to the south.
The 5th AAF provided what cover it could from its inadequate forward airfields, but was further hindered by poor weather over Leyte.
Struble’s Western Visayan Task Force departed Leyte on 12 December in ships of Vice Admiral Thomas C. Kinkaid’s 7th Fleet, under the air protection of 12 fighters from the escort carriers and 35 Vought F4U Corsair land-based fighters of Marine Aircraft Group 12. The convoy was located at 09.00 by Japanese reconnaissance aircraft, and came under attack from 15.00, when an Auchi D3A 'Val' dive-bomber carrying two bombs plunged into Nashville and badly damaged her, with casualties of 133 dead and 190 wounded. The dead included both Struble’s and Dunckel’s chiefs-of-staff, and Dunckel himself was wounded. Nashville retired to Leyte Gulf accompanied by a destroyer. Other kamikaze attacks damaged two tank landing ships and disabled several other vessels. A second wave of attackers, comprising seven kamikaze aircraft escorted by three fighters, attacked the Heavy Cover and Carrier Group at 17.05. Three kamikaze aircraft broke through the combat air patrol and one of these hit Haraden, killing 14 men and wounding 24 others, and forcing the destroyer to return to Leyte Gulf. A third attack on the Slow Tow Convoy scored no hits.
The following day, 14 December, was marked by a Japanese all-out attempt to destroy the invasion force. The Japanese despatched at least 186 aircraft for the attack, but most of these failed to locate the US ships and also suffered heavy losses, at least 46 of their number being shot down. Most of the Japanese airfields were swept by fighters of Vice Admiral William F. Halsey’s Task Force 38 operating to the east of Luzon and were unable to put aircraft in the air. During the night which followed, the convoys were protected by radar-equipped Consolidated PBY Catalina flying boats scouting ahead of the invasion force. The invasion force’s minecraft swept the area around San Jose before dawn, but located no mines.
The land-based aircraft of the USAAF and the carrierborne aircraft of the US Navy had already mounted a major air offensive in an effort to eliminate the kamikaze threat during the first weeks of December, claiming the destruction of more than 700 Japanese aircraft in the air and on the ground, but as these attacks on the Western Visayan Task Force proved, the effort had not been wholly successful.
The ‘Love III’ landing was committed on 15 December, when the availability of clear weather allowed the full exploitation of US air and naval power, which included the six escort carriers, three battleships, six cruisers and many other support warships to flatten the light Japanese resistance at San Jose. The men of the 503rd Parachute Regimental Combat Team came ashore in Mangarin Bay with the landing forces, for their proposed parachute drop had been cancelled as a result of inadequate airstrip facilities on Leyte for their transport aircraft. Destroyers provided fire support for the troop landings and anti-aircraft protection for the ships in the transport area, but nonetheless two tank landing ships LST-472 and LST-738 were struck by kamikaze aircraft, abandoned and scuttled.
The destroyer Moale went alongside the burning LST-738, which was loaded with aviation fuel and ordnance, to rescue members of her crew: several explosions on the LST caused damage to Moale as she pulled away, fragments of hull material up to 2 ft (0.6 m) square putting four holes in the destroyer’s hull. Moale lost one man killed and other 13 wounded, but rescued 88 men from the LST.
The 1,000 Japanese defenders, led by Major General Rikichi Tsukada, commanding the ‘Kembu’ Group in the western central part of the Philippine islands group, and supplemented by some 200 survivors from ships sunk off Mindoro en route to Leyte, were completely outnumbered and outgunned. Some 300 Japanese manning an air raid warning station at the island’s northern end put up a stiff fight against a company of the 503rd Parachute Regimental Combat Team but, with the exception of the inevitable requirement to mop-up the last remnants of the defence with small-scale operations including other landings between 21 December and 22 January 1945, the island had been secured within 48 hours.
The Japanese defence force on Mindoro suffered some 200 killed and 375 wounded, the survivors then eking out a precarious existence in the part of Mindoro which remained outside the US lodgement. The 24th Division lost 18 men killed and another 81 wounded.
Such was the speed and rapid success of ‘Love III’ that by the end of the first day US Army engineers were at work preparing airfields for the invasion of Luzon. Two airfields were completed in just 13 days, and from these US aircraft were able to provide closer direct support for the planned ‘Mike I’ beach-head on Luzon, striking the Japanese airfields from which the kamikaze aircraft operated before these could take off, and facilitating interdiction flights on Japanese shipping between Formosa and the northern and southern parts of Luzon.
Besides providing airfields to support ‘Mike I’, Mindoro served as a base from which the US forces could undertake diversionary operations designed to draw Japanese troops toward the southern part of Luzon and from which elements of the 19th and 21st Infantry could secure other islands in the area. These included Nasugbu Point on Luzon during 29 January, Verde island in the Verde Island Passage between Mindoro and Luzon, Lubang island off the north-west coast of Mindoro on 28 February, and Romblon and Simara islands to the north-east of Tablas island on 11 and 12 February respectively.
The US Navy built a PT-boat base and small port facility at San Jose.
Meanwhile, warplanes of Lieutenant General Koyoji Tominaga’s 4th Air Army and Vice Admiral Shigeru Fukudome’s 2nd Air Fleet, the latter a component of Vice Admiral Denshichi Okawachi’s South-West Area Fleet, continued to attack the US forces almost every day between 16 and 24 December, with particularly heavy attacks on 20 and 21 December. The 20 December raid was a conventional attack by 29 aircraft against newly operational Hill Field, and 11 Japanese aircraft were shot down at the cost of three Republic P-47 Thunderbolt fighters. The raid of 21 December struck a resupply convoy approaching Mindoro and sank LST-460 and LST-749, and also damaged the transport ship Juan de Fuca.
The Japanese also responded by sea. On 24 December Rear Admiral Masatome Kimura’s Penetration Force departed Cam Ranh Bay in occupied French Indo-China with the heavy cruiser Ashigara, light cruiser Oyodo and destroyers Kasumi, Kiyoshima, Asashimo, Kaya, Sugi and Kashi. It was probably intended that this force should by joined by the fleet carrier Unryu, but this ship was sunk by the US submarine Redfish on 19 December off Formosa. The Japanese operation was nonetheless continued, and adverse weather prevented the Americans from sighting the Penetration Force until 16.00 on 25 December, when it had closed to within 200 miles (320 km) of San Jose. The 5th AAF despatched every available aeroplane against the Japanese, and a powerful force of cruisers and destroyers sortied from Leyte Gulf under Rear Admiral Theodore E. Chandler in a last-ditch bid to intercept the Japanese force.
Despite harassment by the US warplanes and PT-boats, the Penetration Force broke through the US defences, bombarded the beach-head for more than 20 minutes, and got away with the loss of the destroyer Kiyoshima. However, the US air attacks were sufficiently distracting to prevent the Japanese from shelling the beach-head with the accuracy which might have inflicted serious damage, and almost all the Japanese ships suffered damage to greater or lesser degrees.
Between 28 and 31 December the Japanese delivered a heavy attack a large reinforcement convoy of 22 tank landing ships, 23 infantry landing craft, 30 PT-boats, three Liberty ship transports, one fuel tanker, the PT-boat tender Orestes, two aircraft tenders, five US Army cargo ships, and three smaller vessels carrying the 21st Regimental Combat Team and screened by nine destroyers. The convoy was attacked almost continually throughout its passage from Leyte. On 28 December a group of six kamikaze aircraft hit the Liberty ships William Sharon and John Burke. The latter was carrying munitions and blew up, while the former was crippled and had to be taken in tow back to Leyte. At 18.30 on the same day, a group of 20 to 30 kamikaze aircraft crippled LST-750, which was scuttled.
On the following day the presence of a powerful combat air patrol prevented any attackers from breaking through, but late on 30 December, as the ships were unloading at San Jose, a group of D3A dive-bombers hit the destroyers Gansevoort and Pringle, the tender Orestes and the tanker Porcupine. Two hours later another group of aircraft sank the Liberty ship Hobart Baker in a conventional bombing attack. Porcupine began to burn heavily at the stern, and in desperation the Americans attempted to torpedo her stern to put out the flames before they reached her cargo, but the attempt failed and Porcupine was burned out.
On 31 December the Japanese heavily damaged the Liberty ships Simeon G. Reed and Juan de Fuca. On the night of 1 January the Liberty ship John Clayton was crippled, and on 4 January the Liberty ship Lewis L. Dyche was hit while carrying a load of munitions and exploded with the loss of all hands.
Thereafter the attention of the Japanese shifted to the 'Mike I' invasion convoy heading toward Lingayen Gulf on the western side of Luzon island. Woodruff, who succeeded the wounded Dunckel on 1 January, made no attempt to secure the whole of Mindoro island, simply establishing a perimeter against Japanese infantry raids in what was in effect a repeat of the tactics used after the 'Cherryblossom' landing on Bougainville in the Solomon islands group.
The Mindoro campaign was costly for the Americans, with 334 air raid alerts in the first 30 days. Post-war assessment based on Japanese sources indicates that about 200 kamikaze aircraft were expended during the campaign. However, the airfields at San Jose provided badly needed air cover for the 'Mike I' landing in Lingayen Gulf, and San Jose became an important staging base for subsequent operations in the southern part of the Philippine islands group.
On 1 January 1945 the Western Visayan Task Force came under the operational control of the 8th Army, the 6th Army having been relieved for the ‘Mike I’ assault against Luzon.