Operation Cartwheel

Action in the Admiralties

The Decision

by James Miller, jr.

First Plans

By the time Halsey's forces invaded the Green Islands, the Southwest Pacific's plans for moves to the Admiralties and Hansa Bay, which had been started in November 1943, were well developed. (GHQ SWPA Warning Instns 3, 23 Nov 43, in ALAMO ANCHORAGE Jnl 1, 23 Nov 43-12 Feb 44.)

Jumbo Map: Seeadler Harbor Area (very slow: 262K)

On 13 February General MacArthur issued operations instructions to the South and Southwest Pacific Areas which called for these commands to gain control of the Bismarck Archipelago and to isolate Rabaul by seizing Mantis and Kavieng about 1 April. (GHQ SWPA 01 44, 13 Feb 44, in GHQ SWPA G-3 Jnl, 13 Feb 44. Unless otherwise indicated this chapter is based on [Maj. William C. Frierson] The Admiralties: Operations of the 1st Cavalry Division (29 February-18 May 1944), AMERICAN FORCES IN ACTION (Washington, 1946))

To General Krueger's ALAMO Force, supported by Allied Air and Allied Naval Forces, he assigned responsibility for the seizure of Seeadler Harbour and Manus, as well as Hansa Bay. Using naval construction battalions and Army service units furnished by Admiral Halsey, Krueger was to start building a major naval base at Seeadler Harbour and to develop the Japanese airfields at Lorengau on Manus and Momote Plantation on Los Negros. MacArthur also warned Krueger to make ready for the drive west along the New Guinea coast.

As in past and future operations, Krueger was responsible for the coordination of plans. But in these orders General MacArthur departed from the previous practice in his area and adopted principles similar to those prevailing in the South and Central Pacific areas. He specified that the amphibious (naval) commander would be in command of all assault forces, ships and troops but not aircraft, until the landing force was established ashore. Then the amphibious commander would pass the command to the landing force commander, who would become again responsible to his normal military superior-- General Krueger in the case of units assigned to the ALAMO Force. (This change was suggested by Chamberlin who felt that previous orders had, in this respect, been unsound. Note, SJC to CINC, 12 Feb 44, in GHQ SWPA G-3 Jnl, 13 Feb 44.)

The operations, as planned, differed from previous ones in another important respect. In one general area three separate naval forces would be operating: Halsey's, Kinkaid's, and the additional forces from Nimitz. Chamberlin therefore suggested that in the event of a major naval action command of these forces be vested in Halsey, who would be the senior admiral present (Ibid.)

This suggestion was accepted, although for some reason it was not followed in similar situations at Hollandia and Leyte.

Forces assigned to General Krueger for the Admiralties totaled 45,110 men. They included:

Southwest Pacific ground units (25,974)

    1st Cavalry Division
    Antiaircraft and coast artillery units
    592d Engineer Boat and Shore Regiment
    1st Marine Amphibian Tractor Battalion
    Engineer, medical, ordnance, quartermaster, signal, and naval base units

Air units: No. 73 Wing, RAAF (2,488)
South Pacific naval construction units (9,545)
South Pacific Army service units (7,103)

These were to be concentrated at Oro Bay and Cape Cretin. The 6th Division was designated as GHQ reserve.

Hansa Bay was supposed to be invaded on 26 April by the 24th and 32d Divisions. There an air and light naval base would assist in the isolation of Rabaul and the Madang- Alexishafen area and would support operations westward. (Memo, Chamberlin for CINC, 9 Feb 44, sub: Outline Plan-Hansa Bay, and Memo, Chamberlin for Comdrs, 9 Feb 44, sub: Hansa Bay-SW Pac Forces, both in GHQ SWPA G-3 Jnl, 9 Feb 44.)

The Target: Enemy Dispositions

The Admiralties, lying 200 miles northeast of New Guinea, 26o miles west of Kavieng, and 200 miles northeast of Wewak, were admirably situated to assist in isolating Rabaul and in supporting the approach to the Philippines.

They contained two airfields as well as a superb harbor. The Japanese had built and used the airfields but, possessing Rabaul, had never made extensive use of Seeadler. This harbor, formed by the horseshoe-shaped curvature of the two major islands, had a surveyed area 6 miles wide, 20 miles long, and 120 feet deep, ample for the fleets of World War II. Guarding the harbor entrance is a line of islets--Koruniat, Ndrilo, Hauwei, Pityilu, and others--which parallel Manus' north coast. (Map 19) (Data in this subsection are derived from [Frierson] The Admiralties; Morison, Breaking the Bismarcks Barrier, PP. 436-37; 8th Area Army Operations, Japanese Monogr No. 110 (OCMH), p. 133; Southeast Area Naval Operations, III, Japanese Monogr NO. 50 (OCMH), 35- 36.)

Manus, the largest in the group, is separated from Los Negros by a narrow strait, Loniu Passage. Forty-nine miles from east to west and sixteen miles across, Manus is a heavily wooded island of volcanic origin. Mangrove swamps cover much of the shore line. A range of mountains, two thousand to three thousand feet in height, extends the east-west length. Many of the streams were navigable for small boats, and nearly all could be forded except when in spate. Principal overland routes consisted of four native tracks: three ran from the north coast over the high country; the fourth extended from Lorengau to the west part of Manus.

Los Negros, much smaller than Manus, is irregularly shaped and cut by several inlets. Papitalai Harbour, an extension of Seeadler Harbour, is separated from Hyane Harbour by a low spit only fifty yards across. Natives had built a skidway over the spit to drag their canoes from one harbor to the other.

Jumbo Map: Los Negros Assault (very slow: 247K)

The center part of Los Negros, in the vicinity of Momote, is flat and fertile. The swampy region north of the skidway had some coconut plantations. West of Momote are three jungled hill masses about two hundred feet high.

The thirteen thousand natives (Melanesian with some Micronesian admixture) lived largely in Los Negros and eastern Manus. Coconut was the standard commercial crop. The natives, who sailed their large canoes with skill, also dived for trochus shell and pearls. The climate--hot and wet--is about the same as that of the rest of the region.

Japanese troops had landed at Lorengau in April 1942 and developed an airfield there. The next year they built a 5,000-foot strip at Momote and improved the Lorengau field. Toward the end of the year, as the Allies advanced to the Markham Valley, the Huon Peninsula, and Cape Gloucester, the Japanese began using the Admiralties' fields as staging points for aircraft flying between Rabaul and Wewak and Hollandia.

Up to now the garrison had consisted of the 51st Transport Regiment, but when the Japanese decided to strengthen Kavieng they also decided to reinforce the Admiralties. Elements of the 14th Naval Base Force, the main body of which was stationed in New Ireland, were sent to Los Negros and Mantis. On 9 December General Imamura directed Adachi to send one infantry regiment and an artillery battalion from New Guinea to be rehabilitated in the Palaus, from where they were to proceed to the Admiralties. (The Admiralties reinained under Imamura's control after the reorganization in March 1944.)

The 66th Infantry reached the Palaus safely, but replacements and reinforcing units en route from Japan were lost to a U.S. submarine. Then Imamura organized an infantry and an artillery battalion in the Palaus out of other replacements. These set out for the Admiralties in January, but their ships were so harried by submarines that they turned back. Imamura therefore arranged with Kusaka for destroyers to carry the 2d Battalion of the 1st Independent Mixed Regiment from Kavieng to the Admiralties. This movement was accomplished on 23-25 January, and at the month's end the 1st Battalion, 229th Infantry, was dispatched. Though it suffered air attack on the way, it arrived safely.

By 2 February the Japanese garrison consisted of the two infantry battalions, the 51st Transport Regiment, and several naval detachments. In command was Col. Yoshio Ezaki, who also led the 51st Transport Regiment. He disposed his main strength on Los Negros to defend Seeadler Harbour and Momote airfield against attack from the north. An Allied attack through Hyane Harbour was not expected because it was small, with so narrow an entrance that landing craft would come under fire as they passed through.

"Prepare for Immediate Reconnaissance in Force"

General Kenney's Allied Air Forces had prepared elaborate plans for supporting the Admiralties invasion from Dobodura and Nadzab. During January and the first two weeks of February his planes bombed the Admiralties and Kavieng, and also continued their attacks against the Wewak airfields so as to keep them out of action and destroy the 4th Air Army's planes. By 6 February Momote and Lorengau airfields were unserviceable, and no planes were present. Antiaircraft fire had stopped completely, not because the guns were destroyed but because Colonel Ezaki, to conceal his positions from the Allies, had ordered his troops neither to fire nor to move about in daylight.

At this time Kenney and Whitehead were eagerly seeking methods by which the whole advance could be made to move more rapidly. Whitehead wanted to get the Admiralties out of the way soon, so that he would have time to concentrate against Wewak and Hollandia in the westward advance. Kenney, who had experience in New Guinea with quick seizures of airfields by light forces, had a scheme in mind for another such operation. Some time before 23 February he told Whitehead to hit Los Negros hard but not to crater the runway. Hoping to force the Japanese to evacuate Los Negros and retire to Manus, he ordered frequent low- altitude photo-reconnaissance missions. (Kenney, General Kenney Reports, P. 358; Craven and Cate, The Pacific: Guadalcanal to Saipan, p. 559.)

The Allies were not yet fully aware that Japanese air resistance in the Southeast Area was almost a thing of the past, and that they had won. They knew, however, that the enemy was weakening. The runways at Rabaul were usually cratered. On 21 February Allied intelligence reasoned that Japanese aircraft were "absconding" from Rabaul, probably to Truk and other bases in the Carolines. (GHQ SWPA G-2 Daily Summary of Enemy Int, and GHQ SWPA G-2 Est of Enemy Sit 700, 20-21 Feb 44, both in GHQ SWPA G-3 Jnl, 21 Feb 44.)

Further, five Seventh Fleet destroyers sank a Japanese transport about one hundred miles east of Lorengau during a sweep on 22-23 February. Survivors testified that they were part of a 400-man detachment of air force ground crews that was being transferred to bases farther north. Three of the destroyers then sank a Japanese destroyer and a cargo ship south of New Hanover, skirted the southwest coast of New Ireland, and steamed safely past Rabaul through Saint George's Channel, which lies between New Britain and New Ireland, on the way back to base. The other two bombarded Kavieng. No Japanese aircraft opposed either group although these waters had formerly been dominated by Japanese air and surface forces.

On 23 February-shortly after the, great Truk raid and the withdrawal of Japanese naval aircraft from the Southeast Area-Whitehead forwarded to Kenney a reconnaissance report from three B-25's that had just flown over Los Negros and Lorengau for ninety minutes. Although they flew as low as twenty feet, they were not fired on, saw no Japanese, no trucks, and no laundry hung out to dry. The airfields were pitted and overgrown with grass. The whole area looked "completely washed out." Whitehead recommended that a ground reconnaissance party go in at once to check. (Rad, Comdr AdVon Fifth AF to Comdr AAF, 23 Feb 44, in GHQ SWPA G-3 Jnl, 23 Feb 44.)

When Kenney received this message he was at his headquarters in Brisbane. Concluding, with Whitehead, that "Los Negros was ripe for the plucking," he hurried to MacArthur's office and proposed to MacArthur, Kinkaid, and part of MacArthur's staff that a few hundred troops carried on APD's seize Los Negros and repair Momote airfield at once, rather than capture Seeadler Harbour, so that they could be reinforced and supplied by air if need be. This should be a reconnaissance in force. If resistance proved too strong the invaders could withdraw. A quick seizure of the Admiralties, Kenney argued, might make possible the bypassing of Kavieng and Hansa Bay. (Kenney, General Kenney Reports, P. 359.)

General Willoughby, in contrast with the airmen, was convinced that the Japanese garrison was fairly strong. His estimate for 95 February placed enemy strength at 4,050. (Note, G-2 to G-3, 25 Feb 44, in GHQ SWPA G-3 Jnl, 25 Feb 44. GHQ SWPA G-3 Monthly Summary of Enemy Dispositions, 29 Feb 44, in GHQ SWPA G-3 Jnl, 29 Feb 44, gives the same figures.)

MacArthur quickly decided in favor of the reconnaissance in force. Next day he radioed orders to Krueger, Whitehead, and Barbey to "prepare for immediate reconnaissance in force." He directed Krueger and Barbey to send eight hundred men of the 1st Cavalry Division and other units aboard two APD's and one destroyer division from Oro Bay to Momote not later than 29 February. If successful the cavalrymen were to prepare the airfield for transport aircraft and hold their positions pending arrival of reinforcements. (Rad, MacArthur to Comdr ALAMO, CG AdVon Fifth AF, and Comdr VII Amphib Force, 24 Feb 44, in GHQ SWPA G-3 Jnl, 24 Feb 44.)

More Action in the Admiralties

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