Battle of Kwajalein

The Battle of Kwajalein was a battle of the Pacific campaign of World War II, fought from 31 January 1944 to 3 February 1944 on Kwajalein Atoll in the Marshall Islands.

After the capture of Makin and Tarawa in the Gilbert Islands, the next step in the United States Navy's campaign in the central Pacific was the Marshall Islands. These islands had been German colonies until World War I, then assigned to Japan in the post-war settlement as the "Eastern Mandates". After the loss of the Solomon Islands and New Guinea in 1943, the Japanese command decided that the Gilbert and Marshall islands would be expendable; they preferred to fight a decisive battle closer to home. However, at the end of 1943, the Marshalls were reinforced to make their taking expensive for the Americans. By January 1944 the regional commander in Truk, Admiral Masashi Kobayashi, had 28,000 troops to defend the Marshalls, but he had very few planes.

By the time Japan entered World War II, The Marshalls (South Pacific Mandate), were already an integral part of the Japanese perimeter of defense. Its facitilies were being utilised as outlying bases for submarines and surface warships, as well as for air staging for future advances being planned against Ellice, Fiji Island, and Samoa.

Actual defenses on the Marshalls, however, were never very substantial or heavily manned. After nearly 10 years of construction, fortifications on the Marshalls lacked considerably when compared with Tarawa, which had been turned into fortress in less than 1 1/2 years. In addition, less than half of the troops stationed there were combat trained, the rest being support and labour troops with little to no combat training. It was not until after the Japanese position in the Solomons and New Guinea began to deteriorate that Imperial Headquarters made plans to strengthen the Marshalls. In fact, by September 1943,the Japanese High Command had written off the Gilberts and Marshalls as lost, deciding that the areas should be to use to fight a delaying action while a new defense perimeter from the Banta Sea through the Carolines and the Marianas. Additionally, combat units were ordered to the Marshalls from Philippines, Manchukuo, and the homeland, with additional air power to be flown in from both the homeland and nearby Truk.

The 6th Base Force, under command of Rear Admiral Monzo Akiyama, and headquarters on Kwajalein, was the principal defense force of the islands. Akiyama, however, had his men spread out over a very wide area, mostly concentrating on the defense of those atols (Jaluit, Mille, Maloeap, and Wojte) that were never considered vulnerable to American attack. Those reinforcement troops that did arrive were quickly dispersed by Akiyama, mainly to the outlying atols. Kwajalein was to remain undermanned, underequipped, and unprepared for the assaults being arrayed against it. Overall Japanese strength on these islands numbered approximatelly 8,000 men, of which less than half were combat effectives. On Kwajalein proper, the troops were made up mostly of labour forces, a good number of those being Koreans. On Roi-Namur, the troops were mostly JNAF land personnel who had little ground combat training and who were underequipped for such a function.

The defense system on the island were mostly in line, with little or no depth. Althougth some fortified areas existed, none were as extensive or well armed as those of Tarawa. In addition, there were several defenses were mostly concentrated on any assault coming from the lagoon side; no coastal defense artillery had been placed on key islets guarding passages to the lagoon, and there was little or no use of mines. Despite shortfalls, efforts to strengthen ground defenses continued, yet Akiyama's greatest defense remained his aerial offensive capability. He had well manned air bases on Roi-Namur, Maloeap, Wojte, Mile and Eniwetok, detached Chitose and 653th Air Corps Mitsubishi A6M fighters with the nearly complete Mitsubishi G3M and G4M bomber base in Kwajalein. In addition, he had some Nakajima A6M2-N and Mitsubishi F1M detached in seaplane bases on Burton, Jaluit, Wojte, Majuro, Taongi, and Utirik. During the month of November, however, both USAAF land-based and US Navy carrier-based bomber attacks, in conjunction with the American assault on the Gilberts, had destroyed 71 of Akiyama's fighters and bombers. Reinforcements flown in from the homeland and Truk replenished most of his losses, but he could expect little additional help in the future. Japanese war industries was falling far short of needed production, affecting all branches of the armed services, including the Japanese Carrier Air Arm, which had long since retreated from the Central Pacific. In fact, the 32 planes flown from the Truk were the last of the carrier aircraft left behind following that retreat. Akiyama was therefore not expected to defeat his adversary, but rather to delay the Allied forces advance while exacting the greatest possible toll upon them.

Expecting the US to attack the outermost islands in the group first, most of the defenders were stationed on Wotje, Mille, Maloelap, and Jaluit to the east and south. This disposition was revealed to the Americans by ULTRA decryptions of Japanese communications, and Nimitz decided instead to bypass these outposts and land directly on Kwajalein. To do this, sea and air superiority were necessary. Accordingly, on 29 January 1944, US carrier planes attacked the Japanese airfield on Roi-Namur, destroying 92 of the 110 Japanese planes in the Marshalls.

Staging through Baker Island airfield Rear Admiral J.H.Hoover's Consolidated B-24 "Liberators" of the Seventh Air Force, quickly set their sights upon their targets. In the beginning, the most important were Mille, the Japanese base closest to the Gilberts and Maloeap, the most powerful enemy bases threatening the upcoming operations. Mille was subject of several attacks through the month of November, causing considerable damage to installations and high losses of aircraft for the Japanese. But Mille remained the only base within fighter reach of the Gilberts and the defenders managed to keep the facilities there operational and reinforced with aircraft. Following the capture of Tarawa, and througth the 19th of December, 106 B-24s dropped a total of 122 tonnes of explosives on Mille's airbase. The largests of those raids came on December 4 when 34 B-24s pulverized the atol in conjunction with carrier-based bombing raids of other parts of Marshalls.in December 18 he initiated renewed strikes against enemy targets on Mille with land-based A-24 Dauntless dive bombers and Bell P-39 Airacobra making their debut in the Marshall air offensive. Japanese losses for the day ammounted to 10 fighters (four on the ground) and four damaged. Other aircraft types participating in the offensive included B-25 Mitchell and Curtiss P-40 Warhawk.

The American forces for the landings were Rear Admiral Richmond K. Turner's 5th Amphibious Force, and Major General Holland M. Smith's V Amphibious Corps, which comprised the 4th Marine Division commanded by Maj. Gen. Harry Schmidt, the 7th Infantry Division commanded by Maj. Gen. Charles H. Corlett, plus the 22nd Marine, 106th Infantry, and the 111th Infantry regiments. The 4th and 7th Divisions were assigned to the initial landings at Kwajalein, while the 2nd Battalion of the 106th was assigned to the simultaneous capture of Majuro Atoll, about 490 km to the southeast. The rest of the 106th and the 22nd Marines were in reserve for Kwajalein, while awaiting the following assault on Eniwetok, scheduled for three months later.

The 7th Infantry Division began by capturing the small islands labeled Carlos, Carter, Cecil, and Carlson on 31 January, which were used as artillery bases for the next day's assault. Kwajalein Island is 4 km long but only 800 m wide. There was therefore no possibility of defence in depth and the Japanese planned to counter-attack the landing beaches. They had not realized until the battle of Tarawa that American amphibious vehicles could cross coral reefs and so land on the lagoon side of an atoll; accordingly the strongest defences on Kwajalein faced the ocean. The bombardment by battleships, B-29 bombers and artillery on Carlson was devastating. The US Army history of the battle quotes a participant as saying that "the entire island looked as if it had been picked up 20,000 feet and then dropped." By the time the 7th Division landed on Kwajalein Island on 1 February 1944, there was little resistance; by night the Americans estimated that only 1,500 of the original 5,000 defenders were still alive.

On the north side of the atoll, the 4th Marine Division followed the same plan, first capturing islets Ivan, Jacob, Albert, Allen, and Abraham on 31 January, and landing on Roi-Namur on 1 February. The airfield on Roi (the eastern half) was captured quickly, and Namur the next day. The worst setback came when a Marine demolition team threw a satchel charge of high explosive into a Japanese bunker which turned out to be a torpedo warhead magazine. The resulting explosion killed twenty Marines and wounded dozens more. Only 51 of the original 3,500 Japanese defenders of Roi-Namur survived to be captured.

The relatively easy capture of Kwajalein demonstrated US amphibious capabilities and showed that the changes to training and tactics after the bloody battle of Tarawa had been effective. It allowed Nimitz to speed up operations in the Marshalls and invade Eniwetok Atoll on 17 February 1944.

The Japanese learned from the battle that beachline defenses were too vulnerable to bombardment by ships and planes. In the campaign for the Mariana Islands, the defense in depth on Guam and Peleliu was much harder to overcome than the thin line on Kwajalein