Operation ‘Stalemate II’ – The US capture of Peleliu (Part 1)

by Chris Chant on 07/05/2012

First wave of LVTs moves toward the invasion beaches in Battle of Peleliu

‘Stalemate I’ was the overall US scheme for the seizure of key islands among the 100 or more islands of the Palau group as part of the ‘Granite’ plan, and was developed in the spring and summer of 1944. These islands formed the main southern anchorage of Admiral Mineichi Koga’s (from 3 May 1944 Admiral Soemu Toyoda’s) Combined Fleet from February 1944, and were desired by Admiral Chester W. Nimitz’s Pacific Ocean Areas command as the Japanese air strength on the main islands was being built up from the remnants of Vice Admiral Junichi Kusaka’s 11th Air Fleet largely destroyed over the operational area of General Korechika Anami’s 2nd Area Army in western New Guinea. Under the overall command of Lieutenant General Hideyoshi Obata’s 31st Army, the Palau islands were garrisoned from March 1944 by one regiment detached from Lieutenant General Shunkichi Ikeda’s 35th Division pending the arrival, during April, of Lieutenant General Sadae Inoue’s 14th Division from China. Eventually the islands’ Japanese garrison totalled 21,000 army and 4,000 navy troops, as well as some 10,000 impressed labourers.

Twin objectives
The US forces were interested in the Palau islands not just as a US stepping stone from New Guinea to the Philippine islands, but also as a means of severing the Japanese chain of support for their forces in New Guinea. For this reason Vice Admiral Marc A. Mitscher’s Fast Carrier Task Force (three carrier task groups supported by six fast battleships, 13 cruisers and 26 destroyers) of Vice Admiral Raymond A. Spruance’s 5th Fleet struck at the islands on 30/31 March in preparation for the US Army’s ‘Reckless’ operation against Hollandia in New Guinea. The destroyer Wakatake and 28 merchant ships totalling 129,807 tons were sunk, some 30 aircraft were destroyed, and the approaches to the main anchorage were mined. Koga was immediately concerned about the newly revealed vulnerability of his Combined Fleet’s main anchorage, and ordered a withdrawal to Tawi-Tawi, between Borneo and the Philippine islands.

Operation ‘Stalemate II’ was the definitive version of ‘Stalemate I’ for the capture of key targets in the Palau islands, and was implemented on 15 September 1944. With the pace of US operations in the central and south-west Pacific areas now increasing and the Philippine islands targeted for assault by combined US Navy and US Army forces during October 1944, it was decided by Admiral Chester W. Nimitz’s Pacific Ocean Areas command to secure advanced bases, that for the US Navy in the Palau islands and that for the US Army on Morotai island, which were to be assaulted simultaneously on 15 September. The ‘Tradewind’ operation against Morotai by Major General John C. Persons’ (later Major General Clarence A. Martin’s) 31st Division met no opposition and succeeded in achieving its objective without difficulty, but this was certainly not the case with ‘Stalemate II’ undertaken against the Palau islands by Admiral William F. Halsey’s 3rd Fleet.

Strategic disagreement
By the summer of 1944 the successes of the US forces in the South-West Pacific and Central Pacific Areas led to disagreement in the US Joint Chiefs-of-Staff about which of two proposed strategies should be adopted to encompass the final defeat of Japan. The strategy proposed by General Douglas MacArthur’s South-West Pacific Area command was posited on the recapture of the Philippine islands followed by that of Okinawa as the stepping stones to a direct assault on the Japanese home islands, while that preferred by Admiral Chester W. Nimitz’s Pacific Ocean Areas command was posited on a more indirect approach in which the Philippine islands would be bypassed, but Okinawa and Formosa would be taken as staging areas for an attack on the Chinese mainland paving the way to invasion of Japan’s southern islands. MacArthur’s and Nimitz’s plans each included the seizure of Peleliu, for different reasons, by Major General William H. Rupertus’ 1st Marine Division. President Franklin D. Roosevelt travelled to Pearl Harbor for a personal meeting with his two most senior commanders in the war against Japan, and selected MacArthur’s plan in preference to that of Nimitz. Before MacArthur’s forces attempted their invasion of the Philippines, however, the Palau islands in general, and Peleliu and Angaur in particular, were to be neutralised and an airfield built to protect the right flank of MacArthur’s assault on the Philippine islands from Japanese air and naval interference from the east.

By the summer of 1944, the Japanese forces in the Palau islands totalled about 30,000 men, centred on Lieutenant General Sadae Inoue’s 14th Division (2nd, 15th and 59th Regiments), which its commander deployed mainly on Babelthuap, the largest of the Palau islands and located at the northern end of the group. Some 11,000 men (2nd Regiment of the 14th Division, and Korean and Okinawan labourers) were stationed on Peleliu. Colonel Kunio Nakagawa, commander of the 2nd Regiment, was entrusted with the task of preparing the island’s defence. After their losses in the Solomon, Gilbert, Marshall and Mariana island groups, the Japanese army had assembled a research team to develop a new combination of strategy and tactics for the defence of islands. The team quickly abandoned the earlier concept of attempting a tenacious and costly defence of the beach area, followed by Banzai charges that were still more costly and had by now been revealed to be fruitless, in favour of tactics that were designed to disrupt any US landing, to form a ‘honeycomb’ system of fortified positions farther inland, to replace the Banzai attacks with co-ordinated counterattacks, and draw the US forces into an attritional campaign that would exhaust the invaders and compel them to commit ever more resources.

In accordance with this new thinking, Nakagawa concentrated his defences inland and, exploiting every feature of the rugged terrain to his advantage, supervised the construction of a system of heavily fortified bunkers, caves, and underground positions. The main strength of Nakagawa’s defence system was based at Peleliu’s highest point, Umurbrogol ‘mountain’, which comprised a number of hills, steep ridges and deep defiles. Located in the island’s centre and dominating the peninsula stretching out north-east from Peleliu’s wider southern half, Umurbrogol overlooked much of the island including the crucial airfield. The Umurbrogol complex contained some 500 limestone caves, connected by tunnels. Many of these were former mine shafts that were turned into defence positions, the engineers adding sliding steel armour doors with multiple openings for artillery and machine guns. The Japanese dug and blasted other positions throughout the Umurbrogol complex for 81- and 150-mm (3.2- and 5.9-in) mortars as well as 20-mm cannon. Further strength was added by the presence of a light tank unit and an anti-aircraft detachment. The cave entrances were built at an angle to improve their ability to survive grenade and flamethrower attacks, and the caves and bunkers were turned into a giant defensive complex by the mass of tunnels that was driven through the centre of the island. This made it possible for the Japanese to evacuate or reoccupy positions as needed, and to take full advantage of interior lines of communication as the US forces advanced. The Japanese also used the location of the likely US landing for the development of an importance defensive feature. The northern end of the landing beaches faced a 30-ft (9.1-m) coral promontory which overlooked the beaches from a small peninsula later known to the US forces as ‘The Point’. Holes were blasted into the ridge to accommodate a 47-mm gun and six 20-mm cannon. The positions were then sealed to leave just a small firing slit facing the assault beaches. Similar positions were created along the 2-mile (3.2-km) stretch of landing beaches. The Japanese also strewed the beaches with thousands of obstacles for the landing craft. These obstacles were mostly mines and heavy artillery shells, buried with their fuses exposed to explode on being run over. One battalion was placed along the beach to defend against the landing, but these defences were meant simply to delay and not to defeat the US landing and advance. The Japanese would then channel the US advance inland to the mauling area between the fortified ridges and hills.

Unchanged US tactics
The US invasion tactics were essentially unaltered from those which had generally succeeded in previous amphibious assaults, despite the fact that the US forces had suffered 3,000 casualties and two months of delay in the face of entrenched Japanese defenders at the Battle of Biak in May and June 1944.

For ‘Stalemate II’ the US planners chose to land on the south-western beaches as these were close to the airfield. Colonel Lewis B. Puller’s 1st Marines was to land at the northern end of the beaches, Colonel Harold D. Harris’ 5th Marines in the centre, and Colonel Herman H. Haneken’s 7th Marines at the southern end; the 11th Marines, the divisional artillery regiment, was to come ashore after the infantry regiments. The plan was for the 1st and 7th Marines to drive inland, proving flank protection for the 5th Marines’ left and right flanks respectively, and thus facilitate the 5th Marines’ advance to take the airfield straight ahead of the centre of the selected landing beach. The 5th Marines were then to push forward to the east coast, where the land is low-lying and swampy, thereby cutting the island in half. The 1st Marines would push north into the Umurbrogol complex, and the 7th Marines would clear the southern end of the island. Only one battalion was left behind in reserve, with the 10,995 men of Major General Paul J. Mueller’s 81st Division of the US Army available for support from Angaur, just south of Peleliu. It was on 4 September that the 17,490 men of the 1st Marine Division departed their base on Pavuvu, just north of Guadalcanal for the 2,100-mile (3380-m) passage across the Pacific to Peleliu. The landing was preceded by the operations of the US Navy’s Underwater Demolition Team, which cleared obstacles from the beaches and their approaches, and then on 12 September warships began their preliminary bombardment of Peleliu.

The revision of ‘Stalemate I’ into ‘Stalemate II’ had taken account of the fact that the main Japanese strength was located in the northern part of the Palau islands, and the US plan was now to take only the two southern islands (Peleliu and Angaur) so that the Kossoi Passage could be cleared of mines and the anchorage used for the forthcoming invasion of the Philippine islands. The target area was softened up by naval gunfire bombardment and air attacks from the surface combatants and escort carriers of Vice Admiral Theodore C. Wilkinson’s Task Force 31 (Joint Expeditionary Force or 3rd Amphibious Force), whose ground forces were incorporated in Major General Roy S. Geiger’s III Amphibious Corps. After the raids by Vice Admiral Marc A. Mitscher’s TF38 on 6/8 September, the naval bombardment of Peleliu and Angaur started on 13/14 September using Rear Admiral Jesse B. Oldendorf’s fire support group comprising the battleships Pennsylvania, Tennessee, Maryland, Mississippi and West Virginia, heavy cruisers Indianapolis, Louisville, Minneapolis and Portland, light cruisers Columbia, Cleveland, Denver and Honolulu, and 14 destroyers. There were also three fleet carriers and five light carriers, and in the pre-lading bombardment these forces dropped 519 16-in (406-mm) and 1,845 14-in (356-mm) shells, as well as 1,793 500-lb (227-kg) bombs on an island of only 5 sq miles (13 km²). Air support was provided by Rear Admiral Ralph A. Ofstie’s Task Group 32.7 of between seven and 11 escort carriers, whose aircraft flew 382 sorties on the day of the landing. On 16 August the destroyer Wadleigh was damaged by a mine in the Kossol Passage.

The attack on Peleliu and Angaur was entrusted to Rear Admiral George H. Fort’s TF32 (Western Attack Force), and on 15 September some 27,490 men of the Northern Attack Force (Major General William H. Rupertus’s 1st Marine Division with the 1st, 5th and 7th Marines plus the 11th Marine Artillery totalling 17,490 men) began to land on Peleliu against a Japanese defence comprising some 10,700 men, centred on the reinforced 2nd Regiment but also including other army elements such as the 346th Independent Battalion of the 53rd Independent Mixed Brigade, the 3/15th Regiment, and a miscellany of field artillery, anti-aircraft artillery and armoured units to a total of 6,500 men. Japanese navy elements on the island included detachments of the 43rd and 45th Base Forces, two anti-aircraft units, three construction battalions, and 1,400 air service personnel, for a total of about 3,000 naval personnel. Another 1,200 or so men arrived later as reinforcements or the survivors of failed raids. The Americans clearly believed that the bombardment was successful, Oldendorf going to far as to claim that the US Navy’s warships had run out of targets. The reality was altogether different, for the vast majority of the Japanese positions emerged from the bombardment completely unscathed: even the battalion left to defend the beaches had suffered only minor losses.

Tight fire discipline
During the assault, the Japanese had maintained a very strict fire discipline to avoid giving away their positions. However, the bombardment did destroy all of the Japanese aircraft on the island, as well as the buildings surrounding the airfield. Yet the Japanese remained in their fortified positions, safe and undetected but poised to tackle the Us forces after they had landed.

The ‘Stalemate II’ landing began at 08.32 on 15 September with the 1st Marines coming ashore in the north on White beach, and the 5th and 7th Marines in the centre and south on ‘Orange’ beach. As other landing craft approached the beaches, they came under a devastating crossfire as the Japanese opened their steel defensive doors and swept the sea with heavy artillery fire, and the positions on the coral promontories guarding each flank fired on the marines with 47-mm guns and 20-mm cannon. By 09.30 the Japanese had destroyed 60 LVTs and DUKWs. The 1st Marines were pinned by heavy fire from ‘The Point’, and Puller escaped only narrowly when a shell hit his LVT. Puller’s whole communications team had already been destroyed on its way to the beach by a hit from a 47-mm high-velocity round. The 7th Marines in the south faced a similar problem with fire from their right flank. Many of their LVTs were destroyed as they approached the beach, leaving their occupants to wade ashore through the coral reef in chest-deep or higher water while being raked by Japanese machine gun fire. The marines’ initial casualties were very high, and many marines who did manage to reach the beach had lost their rifles and other essential gear.

It was the 5th Marines who made the best progress on D-day, largely as a result of their distance from the heavy gun emplacements guarding the Japanese left and right flanks. The 5th Marines pushed forward toward the airfield, but were met by Nakagawa’s first counterattack. The Japanese tank company swept across the airfield to push the marines back, but was soon taken under fire by every available tank, howitzer, naval gun and dive-bomber. Technically obsolete, and lacking both firepower and armour, the Japanese tanks were quickly destroyed together with their accompanying infantrymen. By the end of 15 September the marines held their 2-mile (3.2-km) stretch of assault beach but little else. Their biggest push in the south managed to move about 1 mile (1.6 km) inland, but the 1st Marines to the north had managed very little progress because of the relentless flanking fire from ‘The Point’. The marines had suffered 1,100 casualties (200 dead and 900 wounded) during the day. Rupertus had believed the Japanese would quickly crumble as their perimeter had been broken, but the US forces were still unaware of the change of Japanese tactics and their implications in fighting a protracted defence. On 16 September the 5th Marines moved forward to take the airfield and drive toward toward the eastern shore. They swept across the airfield under heavy artillery fire from the higher land to their north, and suffered heavy casualties. After capturing the airfield, they were able to advance to the eastern side of Peleliu. The marines reached the east coast on 19 September, thereby cutting the defence in two and leaving the island’s southern defenders to be wiped out by the 7th Marines. Then they advanced north and south along this low-lying part of the island, reaching its northern end, along a chain of small islands, on 21 September and then crossing two days later to the small island in the centre of the large bay’s entrance, and arriving at its southern end, just above a smaller bay, by 22 September. Beyond this bay the southern area of the island’s main body was strongly contested by the Japanese, who still occupied numerous pillboxes.

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