Eastern Mandates

[David]

Introduction

World War II was the largest and most violent armed conflict in the history of mankind. However, the half century that now separates us from that conflict has exacted its toll on our collective knowledge. While World War II continues to absorb the interest of military scholars and historians, as well as its veterans, a generation of Americans has grown to maturity largely unaware of the political, social, and military implications of a war that, more than any other, united us as a people with a common purpose.

Highly relevant today, World War II has much to teach us, not only about the profession of arms, but also about military preparedness, global strategy, and combined operations in the coalition war against fascism. During the next several years, the U.S. Army will participate in the nation's 50th anniversary commemoration of World War II. The commemoration will include the publication of various materials to help educate Americans about that war. The works produced will provide great opportunities to learn about and renew pride in an Army that fought so magnificently in what has been called "the mighty endeavor."

World War II was waged on land, on sea, and in the air over several diverse theaters of operation for approximately six years. The following essay is one of a series of campaign studies highlighting those struggles that, with their accompanying suggestions for further reading, are designed to introduce you to one of the Army's significant military feats from that war.

This brochure was prepared in the U.S. Army Center of Military History by Burton Wright III. I hope this absorbing account of that period will enhance your appreciation of American achievements during World War II.

GORDON R. SULLIVAN
General, United States Army
Chief of Staff
Eastern Mandates31 January-14 June 1944

The Japanese attack on Pearl Harbor in December 1941 was both a strategic and a political blunder. Japanese pilots not only failed to destroy the U.S. Navy's most lethal weapons, its aircraft carriers, but they also united the American people behind an Allied war effort that would lead to the defeat of military dictatorships on two continents.

The United States took a year after Pearl Harbor to arm and equip its forces before beginning sustained offensive operations in the Pacific. While formally supporting a plan to give priority to the war in Europe, the "Germany-first" policy, America nevertheless dispatched sufficient men and equipment to the Pacific in 1942 to halt the Japanese juggernaut. By the opening months of 1943 the U.S. Army and Marine Corps had fought and defeated the Imperial Japanese Army at Guadalcanal and, with the Australians, at Papua, New Guinea. At sea the U.S. Navy, although suffering heavy losses, had forced back the Imperial Japanese Navy in the Battles of the Coral Sea and Midway and in the waters around Guadalcanal, throwing it on the defensive. By mid-1943, U.S. political and military planners were developing the plans that would carry Allied military might to the heart of the Japanese Empire.

The primary American commanders in the Pacific developed different strategic concepts for pursuing the war against Japan. General Douglas MacArthur, commander in chief of the Southwest Pacific Area, wanted to advance toward Japan along a New Guinea-Philippines axis. He reasoned that his concept would shield Australia from attack, make the best use of existing bases, and provide land-based support throughout most of the advance. MacArthur also hoped to isolate and bypass several well-fortified enemy bastions, as well as to fulfill his pledge to return to the Philippine Islands. Critics argued that his plan depended on a long and vulnerable supply line, was predictable and therefore subject to heavy resistance, and offered no decisive strategic results.

Admiral Chester W. Nimitz, the commander in chief of the Pacific Ocean Area, wanted to thrust west from Hawaii, using sea power and carrier-based aircraft to seize isolated Japanese islands that could not be easily reinforced by the enemy. Once such footholds were se-
[3]
4-5cure, he would carry the war directly to the Japanese homeland. His critics noted the danger of ignoring Australia as well as the difficulties of operating across extended ocean areas without land-based aircraft. Since both plans appeared feasible, Allied military and political leaders debated the merits of each for many months.


The U.S. Joint Chiefs of Staff (JCS) unveiled their "Strategic Plan for the Defeat of Japan" during the Anglo-American Washington Conference in May 1943. As a result of these deliberations, Nimitz was directed to conduct the primary campaign, following the shorter, more direct approach to Japan that he had advocated. MacArthur was ordered to conduct a secondary, or supporting, campaign that would both complement Nimitz's effort and keep pressure on the Japanese across a wide expanse of territory. Although frequently modified during its existence, the JCS plan provided the blueprint for defeating the Japanese Empire in the Pacific.
Strategic Setting

One of the island groups targeted for invasion in the Joint Chiefs' plan was the Eastern Mandates, better known as the Marshall Islands. Under German control from the late 1890s through the end of World War I, the Marshalls had been assigned to the Japanese as mandates in accord with Article 22 of the League of Nations Charter.

The Marshalls lie in two roughly parallel chains about 100 miles apart. The eastern, or "sunrise," chain contains the large atolls of Mille, Maloelap, and Wotje. The western, or "sunset," chain includes Jaluit, Kwajalein, Rongelap, Bikini, and Eniwetok. Both chains have numerous smaller atolls. An atoll normally consists of a perimeter of flat coral islands surrounded by reefs with a lagoon in the center. The lagoons are generally navigable since the coral reefs usually have breaks which permit seaborne traffic to enter and exit the atoll with comparative ease. There are 32 separate island groups in the Marshalls with 867 reefs, spread over 400,000 square miles of ocean. Kwajalein, the world's largest coral atoll, with over 90 islands, is located in the geographic center of the Marshalls and is approximately 2,100 nautical miles southwest of Pearl Harbor. The islands generally are narrow and flat and only two to three miles in length. Even the larger islands rise only about twenty feet above sea level. Although some of the small islands are barren, most have heavy undergrowth, and the larger ones also have coconut palms, breadfruit trees, and scrub pines. On most islands road networks were primitive or nonex-
6
istent in 1942, but one or more islands in each major group were large enough to accommodate an airstrip. Even prior to World War II the Japanese had constructed barracks, airfields, piers, and other military installations on many of the islands, and during 1942 and 1943 they were hard at work fortifying them further.


Faced with conducting operations across vast stretches of water on mostly unimproved islands, Admiral Nimitz developed an operational concept of seizing one island chain to support operations in the next chain. Before attacking the Marshall Islands, Nimitz's forces therefore had seized Tarawa and Makin in the Gilbert Islands, some 565 nautical miles south of the Marshalls, in November 1943. The U.S. Army's 27th Infantry Division had secured Makin against only light Japanese resistance, but the U.S. 2d Marine Di-
7

vision took strongly fortified and defended Tarawa only after suffering some of the heaviest American casualty rates of the war.

The seizure of the Gilberts, especially the invasion of Tarawa, marked the first time an American force had assaulted a heavily fortified enemy beachhead from the sea, and despite sound amphibious doctrine, problems were apparent. Instances of inadequate air support due to poor communications and coordination, ineffective naval gunfire especially during the preinvasion bombardments, and inadequate quantities of equipment and materiel, as well as a shortage of amphibian tractors, all cost lives and demanded immediate solutions for the rest of the campaign. However, the landings, especially those at Tarawa, showed that the U.S. Navy and amphibious forces were capable of securing such isolated outposts with relative speed despite strong opposition.

The U.S. victories at Tarawa and Makin achieved the mission of reducing the distance aircraft would have to travel to reach the Marshalls. U.S. warplanes could now conduct and carry out combat and photographic missions deep within enemy territory. Without that advantage, the campaign against the Marshalls, Operation Flintlock, would have been much more difficult and costly.
Operations

Just as debate surrounded American strategy for reconquest of the Pacific, so too did it affect the more specific plans to secure the Marshall Islands. The JCS War Plans Committee recommended seizing Wotje and Maloelap at the northern edge of the Marshalls, with subsequent attacks on other major islands once initial operating and logistical bases had been established. Rear Adm. Richmond Kelly Turner, commander of the Fifth Amphibious Force, agreed with the Joint Chiefs' planners, as did Marine Corps Maj. Gen. Holland M. Smith, commander of the V Amphibious Corps, and Vice Adm. Raymond A. Spruance, the Fifth Fleet commander. Admiral Nimitz, however, disagreed and instead proposed making Kwajalein, in the center of the Marshalls, the primary objective. Simultaneous air attacks on Kwajalein, Wotje, and Maloelap would neutralize more than 65 percent of the enemy aircraft facilities in the islands, but there would be only a single landing. Nimitz argued that a bold thrust at the heart of the Marshalls would both surprise the Japanese and allow the development of a base from which other occupied islands could
8

be easily neutralized. Concentrating resources on a single decisive landing also would reflect the lessons of the Tarawa battle.

In making his decision, Nimitz had the benefit of intelligence reports not available to his subordinates. In early 1943, Allied cryptographers had achieved a quantum breakthrough in cracking Japanese military codes. Code-named ULTRA, the deciphered intercepts told Nimitz that the Japanese had shifted the bulk of their fighting forces to the outer Marshall Islands, anticipating an attack on the periphery. His decision to strike directly at Kwajalein was thus eminently sensible. He selected 17 January 1944 as the invasion date for Kwajalein, but because of supply and training difficulties he subsequently rescheduled the assault for 31 January.

By early 1944, Nimitz's subordinates had more than sufficient sea, air, and ground forces available to carry out the conquest of the Marshall Islands. The U.S. Fifth Fleet, the main strike arm in the Central Pacific, in the fall of 1943 had 6 heavy, 5 light, and 8 escort aircraft carriers. Additionally, the fleet possessed 12 battleships, including 5 new ships, and 9 heavy and 5 light cruisers. Fifty-six destroyers rounded out the considerable combat power of the fleet.

The principal landing force for the Kwajalein operation was the Fifth Fleet's Fifth Amphibious Force, commanded by Admiral Turner. Based on experience gained in earlier operations, Turner controlled the transport ships, cargo vessels, landing craft, and landing ship docks, but he also commanded the destroyers, escort carriers, cruisers, and battleships that would directly support the assault. Land-based naval aircraft were under the command of Rear Adm. John H. Hoover.

General Smith, commander of the V Amphibious Corps, controlled the ground forces committed to the operation. These were the newly organized 4th Marine Division, then training in the United States; the independent 22d Marine Regiment from Samoa; the Army's 7th Infantry Division, which had participated in the seizure of Attu and Kiska in the Aleutian Islands; and the 2d Battalion, 106th Infantry, 27th Infantry Division. The rest of the 106th and the 111th Infantry were designated as a seaborne reserve. Maj. Gen. Harry Schmidt commanded the 4th Marine Division, while Maj. Gen. Charles H. Corlett commanded the 7th Infantry Division. The 22d Marines was commanded by Col. John T. Walker, and the 2d Battalion, 106th Infantry, by Lt. Col. Frederick B. Sheldon.

While the Allies settled their plans, the Imperial Japanese Navy and Army high commands were reacting to the naval and land de-
9

feats which had started with Guadalcanal and Midway in 1942. By September 1943 they had decided to shrink their defensive perimeter around the Japanese home islands. With the Solomons and portions of New Guinea already lost, they designated the Gilbert and Marshall Islands as expendable outposts, but they decided to reinforce them strongly to make the price of conquest higher. In the last quarter of 1943 the Japanese thus dispatched additional ground forces to the Marshalls, distributing them among the outer islands, as ULTRA revealed.

Within the Marshalls, Kwajalein was the headquarters for the 6th Base Force, which administered the islands and was commanded by Rear Adm. Monzo Akiyama. His headquarters was, in turn, subordinate to the Japanese 4th Fleet, based at the fortified island of Truk. The commander of the 4th Fleet was Vice Adm. Masashi Kobayashi, who had received responsibility for Wake Island, Guam, the Gilbert Islands, Nauru, and Ocean Island in addition to the Marshalls shortly after the attack on Pearl Harbor.

Admiral Kobayashi commanded a fleet in name only. The old Japanese light cruisers Naka, Isuru, and Nagara and the 22d Air Flotilla were the only major combat forces he controlled. lsuzu and Nagara had both been damaged by U.S. naval air prior to the invasion of Kwajalein and had been withdrawn for repairs. Just before Operation FLINTLOCK commenced, 4th Fleet personnel in the Marshalls totaled 28,000 including Korean laborers who were building fortifications.

In fact, the U.S. assault on the Marshalls had begun on 20 November 1943. Because Mille Atoll in the eastern chain of the Marshalls was within Japanese fighter range of the Gilberts, Nimitz had attacked the atoll even before the U.S. Army and Marine forces stormed ashore at Makin and Tarawa. Although the Japanese lost seventy-one planes in the Marshalls that month, most were immediately replaced from Truk or the Japanese homelands. Taroa airfield on Maloelap became the target of American air attacks starting on 26 November, but it remained an operational field until 29 January 1944. Airfields on Jaluit and Wotje were then lightly attacked in early January, as was the entire island of Kwajalein.

As D-day for the Marshalls approached, attacks on Japanese airfields on the islands accelerated. The Japanese had 110 operational planes in the Marshalls on 25 January, but ULTRA intelligence reports pinpointed their location. In a single strike on 29 January, Nimitz's forces destroyed or damaged ninety-two enemy
10

aircraft on Roi-Namur. By D-day, 1 February 1944, only fifteen Japanese planes in the Marshalls were operational. The attackers therefore now had absolute air superiority.

Although the Japanese had expected an American fleet to appear somewhere in the Marshall Islands, they were surprised when one arrived off Kwajalein. Since Imperial Headquarters in Tokyo had reasoned that the American forces would begin at the outer islands and work inward toward Kwajalein, the building of fortifications on that island had received little priority. In addition, the Japanese believed that any landing would come from the seaward side of an island, as opposed to the lagoon side, and they had oriented their defenses in that direction. Only after receiving intelligence reports from Tokyo concerning the capabilities of the American LVT (landing vehicle, tracked), which had demonstrated its ability to climb over coral reefs, were they now finally beginning to construct defensive positions on the lagoon side of many islands. But ultimately, little in-depth defense was possible because most of the islands were so narrow.

Nimitz's plan for the capture of the Kwajalein Atoll was relatively straightforward. The 4th Marine Division was ordered to capture Roi-Namur and other islands in the northeast quadrant of the atoll, while the Army's 7th Infantry Division was to seize the island of Kwajalein itself (44 nautical miles south of Roi-Namur) in the extreme southeast end of the atoll. Additionally, Admiral Spruance received approval to seize Majuro on the eastern edge of the Marshalls in order to provide a fleet base and airfield for subsequent operations. The 2d Battalion of the 106th Infantry was assigned this mission.

The island of Kwajalein is two and one-half miles long and 800 yards wide for most of its length, tapering to 300 yards wide at its northern end. The seaward side had long been fortified, but since the enemy had also been erecting defenses on the lagoon side, General Corlett decided to avoid a frontal assault. His 7th Infantry Division was to come ashore on the western end of the island, which had a beach 400 yards deep, and attack with two regiments abreast. On 31 January, the day before the assault, his forces were also scheduled to seize four small islands surrounding Kwajalein to serve as artillery bases and to ensure unimpeded access to the lagoon. General Schmidt's plan for capturing Roi-Namur was similar. His forces would seize five islands surrounding his main objective on 31 January and conduct their primary landing on 1 February.
11
Japanese defenders on Kwajalein and the nearby islands totaled 5,000, with another 4,000 on Roi-Namur. Only about half were combat troops. Kwajalein had more than a hundred buildings and an airfield with a 5,000-foot runway with various taxiways and ramps capable of handling large numbers of fighters and bombers. The island also had docks and a long pier.


Since large portions of Kwajalein were covered by thick vegetation, a complete intelligence report on potential defenses was impossible. Aerial photography provided excellent views of beaches and open areas, but it could not penetrate the thick brush and palm trees to reveal what fortifications lay beneath. General Corlett had to rely on the belief of U.S. intelligence analysts that Japanese defenses on the island were substantial.

The Americans were well prepared. The designated invasion forces had received specialized training in advanced amphibious techniques, marksmanship, and jungle warfare. Captured Japanese weapons had been fired during practice landings so that troops could recognize their sounds. Detailed intelligence briefings relating to weapons, fortifications, garrison strength, and the type of resistance expected on Kwajalein led commanders to prepare bangalore tor-
12
pedoes, light explosives, and satchel charges containing twenty-five pounds of TNT for use against reported concrete and log bunkers. Both Army and Marine Corps leaders were determined that the costly problems of Tarawa would not be repeated in the Marshalls.


Logistics had also received careful attention. The logistics plan called for the task force to carry 42 days of rations, 5 days of water, 10
13

units of fire (a unit of fire equated to a weapon's expected expenditure of ammunition in a single day of combat) for antiaircraft guns and 105-mm. howitzers, 8 units of fire for other categories of ammunition, and 30 days of other supplies. Leaving nothing to chance, Special Service supplies included 50 harmonicas and 7 ukuleles. The invasion force seemed properly equipped for any eventuality.

The 7th Infantry Division's Cavalry Reconnaissance Troop and Company B, 111th Infantry, opened the Army's operations in the Marshalls on 31 January. At 0330, using rubber assault boats to travel 800 yards from transports to the shore, they attacked and captured the islands of Cecil and Carter and secured the Cecil Pass into the Kwajalein lagoon. They encountered only scattered resistance, killing twenty-one Japanese while suffering only one wounded.

At daybreak units of the 7th Infantry Division's 17th Infantry assaulted two other small islands, Carlos and Carlson. Both were needed to provide artillery platforms for the coming attack. Resistance on both islands was nearly nonexistent, and the operations took less than three hours. At 1125 the 7th Division's artillery began landing four battalions of 105-mm. howitzers and one battalion of 155-mm. howitzers. The preinvasion bombardment of Kwajalein began that afternoon at 1500.

Battleships and heavy cruisers joined the preinvasion bombardment at first light on 1 February, firing 7,000 rounds of 14-inch, 8-inch, and 5-inch ammunition during the period leading up to the assault. Exploding shells and tall columns of black smoke blanketed Kwajalein from end to end. The 7th Division artillery on Carlson fired 29,000 rounds at Kwajalein in support of the landings, and the Army Air Forces added six B-24 bombers from bases at Apamama to the effort, dropping fifteen 1,000- and 2,000-pound bombs on Kwajalein's fortified areas. In addition, for the first time combined Army-Navy underwater demolition teams were used to search the beaches for underwater obstacles and mines. In the case of Kwajalein, none were found.

The collective power of the preinvasion bombardment by the Army, Navy, and Air Forces was literally overwhelming. The participants later described the naval gunfire as "devastating�the entire island looked as if it had been picked up 20,000 feet and then dropped�All beach defenses were completely destroyed, including medium and heavy anti-aircraft batteries."

The 32d and 184th Regimental Combat Teams of the 7th Infantry Division began landing at 0930 on 1 February. LVTs, LCIs
14
The effects of preinvasion bombardmenton Kwajalein. (National Archives)

(landing craft, infantry), and DUKWs, new amphibious trucks, ferried troops and equipment ashore. Gunboats fired when landing craft neared the beach, but enemy mortars and automatic weapons still greeted the troops when they stormed ashore. However, the impact of the preinvasion bombardment was evident. Engineers had only one pillbox to destroy on the beach; the others were reduced to ruins. Despite rubble from trees and fortifications, and craters from bombs and naval gunfire, the first four waves of the assault force were ashore by 0945.

As the Americans moved inland, armored amphibian tractors with 37-mm. guns and flamethrowers provided support. By nightfall six infantry battalions supported by four medium tank companies were ashore, having encountered little effective resistance. That evening Japanese troops executed scattered counterattacks, but American artillery kept any large formations from gathering momentum. Infiltration by small Japanese units caused some intermittent combat for most of the night, though by midnight re-
15

ports indicated that no more than 1,500 of the island's original defenders remained alive.

On the next morning, 2 February, reserve battalions of the 32d and 184th Regimental Combat Teams prepared to pass through the units landed on D-day to continue the attack. The battleship Idaho, the cruiser Minneapolis, 4 destroyers, and 5 Army artillery battalions delivered preparatory fires, and 15 Navy dive bombers hit targets at 0800 as the Americans moved out. Tank-infantry teams then attacked the remaining Japanese pockets of resistance. That night scattered groups of the enemy, however, continued to emerge to harass rear areas, forcing units to defend themselves in all directions.

By the morning of the third day there were approximately 300 Japanese in the unconquered 1,000 yards of the island. Organized resistance ended shortly thereafter as the Americans finished their sweep of the island, although both regimental combat teams spent the remainder of 4 February mopping up. Each enemy bunker, trench, and building had to be checked and rechecked for Japanese soldiers who had evaded initial capture or death. The island had been secured at a minimal cost. U.S. forces suffered 177 killed and 1,000 wounded on Kwajalein, but only 125 Korean laborers and 49 Japanese survived as prisoners. Americans estimated that 50 to 75 percent of the Japanese had been killed in the preparatory bombardments. Earlier intelligence reports that the island had substantial defenses proved to be exaggerated. Most of the fortifications clearly had been hastily constructed.

As the fighting progressed from one end of Kwajalein to the other, the 7th Division quickly began to consolidate its prize. Support and engineer troops landed and began to rebuild the island as an American base. Just days after the cessation of fighting Kwajalein's airfield was functioning, and American planes were attacking islands in the Marshalls still under Japanese control. Elsewhere division troops secured adjacent parts of the Kwajalein Atoll.

Chauncey Island northwest of Kwajalein Island fell on 2 February. Casualties were 14 Americans wounded and 125 Japanese killed, mostly from shelling. At 0930 on 3 February the 17th Infantry assaulted Burton Island. Although so small (1,800 yards by 250 yards) that the Americans could employ only four medium tanks abreast, Japanese resistance was fierce. Determined enemy soldiers fought from bunkers until killed by tanks or engineers using demolitions and flamethrowers. The one-and-a-half-day op-
16Flamethrower in use against a Japanese blockhouse.(National Archives)

eration cost the Americans 7 killed and 82 wounded; the Japanese lost 450 killed, with 7 captured.

While Burton was being subdued on 3 February, other elements of the 7th Infantry Division seized the tiny coral outcroppings of Buster and Byron, located between Kwajalein and Burton, without opposition. On 4 February American forces landed on Burnet and Blakenship Islands, located to the north of Burton. On the former, forty natives cheerfully submitted to capture. On Blakenship a small number of marooned Japanese sailors and Korean laborers had to be subdued with clubs and bayonets before the island could be declared secure.

Over the next few days the remaining islands in the southern portion of Kwajalein Atoll were seized with only limited effort. Bennett Island was an exception. There, Japanese in pillboxes and dugouts fanatically resisted. Rather than expend American lives, tanks were brought ashore, and the enemy was soon subdued. American casualties were 1 killed and 2 wounded, while the enemy
17
Marines attack a blockhouse on Roi-Namur. (National Archives)

lost 94 killed. For the entire southern Kwajalein operation, American casualties were 142 killed, 845 wounded, and 2 missing. The best estimate of enemy losses was 4,938 dead and 206 captured, of whom 127 were Korean laborers.

Meanwhile, the marines were wrapping up their assigned missions in the sixty-two islands in the upper half of the atoll. On 31 January the 4th Marine Division invaded five islands: Ivan, Jacob, Albert, Allen, and Abraham. These five flanked Roi-Namur, the main objective, and like Carlson in the south were to be artillery platforms. By the end of the day the islands were secure, and four battalions of artillery and a considerable number of mortars had been emplaced. Capturing the islands cost the lives of 18 marines, with 8 missing and 40 wounded, while estimates placed Japanese losses at 135 killed.
18

On 1 February the 23d and 24th Marine Regiments began the assault against Roi-Namur. Roi, the objective of the 2d Battalion, 23d Marines, was basically an airfield with little cover and few fortifications, connected to Namur by a narrow causeway. As a result of the preparatory bombardment, about 250 of the 400 Japanese on the eastern half of the island were killed. Despite choppy waters and inexperienced troops, the invasion was successful. Resistance was very light, and American losses totaled 3 killed and 11 wounded during the one day it took to secure the island.

The 24th Marines had tougher going. Namur's topography favored its defenders. Not only were there numerous buildings and bunkers, but much of the island was covered by thick brush which had only been further tangled by the substantial preliminary bombardment. The early-model radios became water-soaked and inoperative, thwarting effective communications between units, and the logistical supply of the troops ashore still experienced problems. The invading marines, following delays caused by inexperienced boat crews, landed on 1 February at 1133 against initially light Japanese resistance. The Americans had advanced about three to four hundred yards inland when a tremendous explosion occurred. The resultant concussion and the large falling fragments of concrete and metal killed twenty marines and wounded fifty others. A Marine demolition party had unknowingly blown up a Japanese torpedo magazine. The explosion acted as a goad to the Japanese defenders who launched localized counterattacks. These events brought the marines' advance to a temporary halt, but they quickly recovered, pushed on, and by nightfall two-thirds of the island was in friendly hands.

As on Kwajalein, the Japanese harassed the Americans on Namur throughout the night. When approximately 100 Japanese soldiers launched the one serious attack, most of them were killed in hand-to-hand fighting. At dawn the marines continued their assault, and by 1215 they had secured the island. Following mopping-up operations on the small islands near Roi-Namur, Kwajalein Atoll was declared secure. The 4th Marine Division suffered a total of 737 casualties, including 190 killed, while estimated enemy losses totaled 3,472 dead, with 40 Korean laborers and 51 Japanese captured.

On the same day that the first landings were being made on Kwajalein Atoll, Admiral Spruance also initiated Operation SUNDANCE, an assault against Majuro Atoll to secure additional air and sea bases. Approximately 265 nautical miles southeast of Kwajalein, Majuro possessed the largest potential fleet anchorage in the
19

Central Pacific. The Army's 2d Battalion, 106th Infantry, 27th Infantry Division, and the Marine V Amphibious Corps' Reconnaissance Company were charged with the mission. The marines were to land, locate that Japanese troops, and eliminate them. The 106th Infantry was to provide reinforcements if required. About 400 Japanese were reportedly defending the area.

SUNDANCE proved almost a nonevent. When some marines went ashore on the outlying islands of Dalap and Darrit, they found an English-speaking native, Michael Madison, who related that the Japanese garrison had left Majuro almost a year earlier. Madison's information proved accurate. On Majuro the marines found a lone Japanese warrant officer who had been left as a caretaker. With his capture, the island was declared secure.

The seizure of Kwajalein, Roi-Namur, and Majuro with comparatively light casualties permitted Admiral Spruance to accelerate the pace of operations in the Marshalls. Some 10,000 troops of the 22d Marines and the two battalions of the Army's 106th Infantry that had been held back as a reserve for the Kwajalein Atoll operation had not even been committed to battle. Spruance therefore moved up the invasion of Eniwetok Atoll, code-named Operation CATCHPOLE, from 1 May to 17 February. The Eniwetok Atoll includes Eniwetok Island and a number of other islands including Parry and Engebi. Covering 383 square miles, it is the second largest atoll in the Marshalls. Since plans called for it to become a major fleet base for upcoming operations in the Central Pacific, Spruance regarded its seizure as critical to the success of his Pacific strategy. Although he initially believed that there were only 700 defenders scattered through the atoll, ULTRA intelligence soon convinced him that the garrison had been reinforced.

The Japanese had not fortified Eniwetok Atoll until 1944. But as the scope and direction of the American Central Pacific strategy became apparent, they greatly strengthened the atoll's defense with the 1st Amphibious Brigade about six weeks prior to the U.S. invasion. Its commander, Maj. Gen. Yoshimi Nishida, attempted to construct a uniform defensive system throughout the atoll. However, his efforts were slowed by frequent American air attacks which damaged freshly built defensive positions, allowed Japanese soldiers and sailors little time to rest, and restricted incoming supplies. The fortifications that the defenders finally managed to erect consisted generally of central defensive positions with "spider" holes radiating out from them. Dense foliage on the island con-
20
cealed their extent from U.S. aerial reconnaissance. Yet once again the size of the atoll made a defense in depth impossible, and Nishida and his officers knew that their survival depended on destroying assault troops as close to the beach as possible.


The preliminary phase of the Eniwetok Atoll invasion began on 17 February 1944. To isolate the target area, Spruance launched two massive carrier strikes against the Japanese island fortress of Truk, some 700 miles to the west, on 17-18 February. The air attacks destroyed several hundred aircraft, the bulk of the Japanese air power in the region, as well as twenty transport ships and several combat and auxiliary vessels, making any assistance to the Eniwetok defenders virtually impossible. Meanwhile the preinvasion naval bombardment of the atoll had begun at 0659 on 17 February. Simultaneously Canna and Camellia, two nearby islands, were occupied and immediately converted for use as artillery plat-
21
Landing craft pass supporting warships during the invasionof Eniwetok. (National Archives)

forms to harass the next target, Engebi Island, northwest of Eniwetok, with sporadic fire around the clock. On that same day, underwater demolition teams checked the beaches off Engebi but discovered no underwater obstacles.

Phase II of the operation began promptly on the morning of 18 February when the 22d Marines landed on Engebi, with the Army's 106th Regiment acting as shipboard reserve. Two battalions of marines, supported by tanks and a cannon company from the 106th Infantry, landed at 0844 and quickly moved inland 100 yards. Opposition was light, and any resistance was immediately bypassed. By 0925 naval gunfire was halted, and in six hours the marines had secured the island. Casualties were 85 killed or missing and 521 wounded, compared to Japanese losses of 1,276 killed and 16 captured.

From prisoners and documents captured on Engebi, U.S. intelligence learned that Eniwetok Island proper was defended by only about 550 enemy soldiers and some 200-300 administrative and support personnel. Based on this information, Rear Adm. Harry W. Hill, the Eniwetok task group commander, directed the 1st and 3d Battal-
22

ions of the 106th Infantry, supported by Marine Corps tanks, to land simultaneously after a relatively light preparatory bombardment.

The naval bombardment began promptly at 0719, 19 February, but its brevity proved a mistake. Few of the Japanese defensive works were destroyed, and the first wave of the assaulting force experienced difficulties from the start. As the LVTs hit the beaches, they were blocked from moving inland by the terrain and heavy automatic weapons fire. Once the 106th's forward momentum was stopped, the Japanese quickly counterattacked, supported by accurate mortar fire and led by enthusiastic Japanese officers. The assaults were repulsed after a number of fierce hand-to-hand engagements.

In view of the strength and determination of the enemy resistance, Admiral Hill ordered the 3d Battalion, 22d Marines, ashore. But even with these additional forces committed to battle, fighting continued until 21 February, D plus 4, when the island was finally secured. Total American casualties, predominantly Army, were 37 killed and 94 wounded; Japanese losses were in excess of 800.

The final phase of the Eniwetok operation was the seizure of Parry Island by the 22d Marines. The amphibious assault, originally scheduled for 17 February, was delayed for three days as a result of the difficulties encountered in seizing Eniwetok Island. But the delay allowed Hill to orchestrate a much more extensive preparatory bombardment. While the Army's 104th Field Artillery Battalion took Parry under fire from Eniwetok Island, the battleships Tennessee and Pennsylvania and the heavy cruisers Indianapolis and Louisville pounded it from the sea. Naval gunfire totaled 944.4 tons of shells in three days. The 104th Artillery added 245 tons to the bombardment, and air-delivered bombs raised the total by another 99 tons of munitions. In contrast, only 204 tons of ordnance had been expended earlier on Kwajalein. American commanders were determined that casualties would not result from a lack of adequate preinvasion bombardment.

At 0900 on 22 February the 22d Marines stormed ashore. Resistance was similar to that encountered on Engebi. There were no major counterattacks, and small groups of the enemy were identified and quickly eliminated. Three Japanese light tanks engaged the marines on the beaches, but they were quickly destroyed without American losses. Nevertheless Japanese resistance seemed to stiffen after their tank attack, and the marines requested naval gunfire. The first salvo fell short and caused extensive friendly casualties, but the rest struck the enemy formations and broke the back of the de-
23

fenders. Parry was declared secure by the commander of the 22d Marines at 1930. Total American casualties in the battle for Eniwetok Atoll were 262 killed, 757 wounded, and 77 missing. Japanese losses amounted to more than 2,000 dead.

Following Parry's seizure, the marines secured the remaining, more lightly defended islands in the Marshalls. Code-named FLINTLOCK JR., these missions were completed with relatively few casualties against only light resistance. Elsewhere, the islands of Wotje, Mille, Maloelap, and Jaluit, heavily defended by the Japanese, were effectively isolated, and their occupants were left to starve or to be bombed into submission until the war ended. The Eastern Mandates Campaign formally ended on 14 June 1944, although ships and planes would operate from bases in the Marshall Islands long after the war was over.
Analysis

The conquest of the Marshall Islands demonstrated the soundness of American amphibious doctrine, albeit on a small scale. As with earlier operations, American planners acquired much experience in the campaign and applied new techniques which would be shaped and refined for subsequent operations. Two of the most important lessons involved dose air support and naval gunfire. Before 1944 continuous support from those services was more the exception than therule. With the destruction of Japanese naval and air forces as the war progressed, and given American industry's tremendous output in ships and planes, the possibility of greatly increasing air and naval preinvasion fire support became both feasible and desirable.

Another tactical advance was the introduction of specially equipped headquarters ships. Although such vessels had already appeared in the Mediterranean, they were first used in the Pacific during the Marshall Islands landings. Although no more than transport or supply vessels equipped with special command and communications facilities, they allowed commanders, both afloat and ashore, to direct multiple amphibious operations independent of the primary fleet command ship. In the Kwajalein operation, the USS Rocky Mount aptly demonstrated the value of this innovation by easily handling the communications for five separate commands engaged in the landings.

The LVT, or Alligator, performed with the same versatility as it had at Tarawa. Lightly armored but heavily armed, these tracked
24
"Radio Communications" by Edward A.Sallenback. (Army Art Collection)

amphibians brought squads of men from ship to beach and then moved them inland when enemy fire was light. When the troops debarked, the LVTs returned to the ships to pick up additional reinforcements. They could also act as supply vehicles and ambulances or in a dozen other useful roles. The DUKW, half boat and half truck, complemented the LVT. Quickly dubbed the "Duck" by American foot soldiers, it greatly assisted in the buildup of supplies and materiel on the beaches.

As the American forces perfected their tactics and their landing craft and equipment, the Japanese changed the nature of their defensive operations as well. Unfortunately for them, the results were often disappointing. In the Marshall Islands the defenders relied on thin beachline defenses with troops designated for immediate counterattack. This type of defensive arrangement was totally inadequate. The weight of the American war machine was too heavy, and the firepower brought to bear on the beachheads was too great. The Japanese were nevertheless capable of making radical
25

adjustments in their defensive postures. Saipan and Iwo Jima, considerably larger than the Marshall Islands, would be difficult and costly to take as a result.

The relatively easy seizure of the Marshalls and the effective neutralizing raids on the Japanese fortress of Truk proved the soundness of Nimitz's decision to use the Central Pacific as the best route to Japan. By neutralizing and bypassing Truk, Nimitz saved many lives with no loss of tactical advantage. The Marshalls provided the same facilities as Truk for both fleet anchorages and airfields for future operations. In addition, the units designated for a possible landing on Truk�two Marine divisions and one Army division plus assorted independent regiments�were able instead to begin training for the seizure of the Marianas, where plans called for Saipan and Tinian Islands to become long-range bomber bases for a massive aerial campaign against the Japanese home islands.

The quick seizure of the Marshall Islands allowed Admiral Nimitz to advance the date for the invasion of the Marianas by twelve to thirteen weeks. At the same time, Japanese preparation time for the defense of islands like Saipan and Tinian was shortened, and many of the U.S. units that had participated in the Marshalls operation, still relatively intact, were available for the Marianas invasion. The overall importance of the rapid seizure of the Eastern Mandates thus cannot be overestimated. The Marshalls were not only a proving ground for new tactics and innovations but also a critical step in a chain of events that would lead to the Japanese surrender at Tokyo Bay.
26
Further Readings

A number of official histories provide carefully documented accounts of the Marshalls operations. They include Philip A. Crowl and Edmund G. Love, Seizure of the Gilberts and Marshalls (1955), a volume in the series United States Army in World War II; S. L. A. Marshall, Island Victory (1945); and Robert D. Heinl, Jr., and John A. Crown, The Marshalls: Increasing the Tempo (1954). Naval actions and support for the Marshalls operation can be found in Samuel Eliot Morison, History of United States Naval Operations in World War II, volume 7, Aleutians, Gilberts, and Marshalls (1951). Marine operations are described in Henry I. Shaw, Jr., Bernard C. Nalty, and Edwin T. Turnbladh, History of the U.S. Marine Corps Operations in World War II, volume 3, Central Pacific Drive. Edward J. Drea's work, MacArthur's ULTRA: Codebreaking and the War Against Japan, 1942-1945 (1992), contains an excellent account of Allied cryptology operations in the Pacific.

CMH Pub 72-23

Cover: Landing on Carlson Island.

(National Archives)