World War II: Battle of Kwajalein

The Battle of Kwajalein occurred January 31 to February 3, 1944 in the Pacific Theater of World War II (1939 to 1945). Moving forward from victories in the Solomons and Gilbert Islands in 1943, Allied forces sought to penetrate the next ring of Japanese defenses in the central Pacific. Attacking into the Marshall Islands, the Allies occupied Majuro and then commenced operations against Kwajalein. Striking at both ends of the atoll, they succeeded in eliminating the Japanese opposition after brief but fierce battles. The triumph opened the way for the subsequent capture of Eniwetok and a campaign against the Marianas. 

Background

In the wake of the American victories at Tarawa and Makin in November 1943, Allied forces continued their "island-hopping" campaign by moving against Japanese positions in Marshall Islands. Part of the "Eastern Mandates," the Marshalls were originally a German possession and were awarded to Japan after World War I. Considered part of the outer ring of Japanese territory, planners in Tokyo decided after the loss of the Solomons and New Guinea that the islands were expendable. With this in mind, what troops were available were shifted to the area to make the islands' capture as costly as possible.

Japanese Preparations

Led by Rear Admiral Monzo Akiyama, Japanese forces in the Marshalls consisted of the 6th Base Force which initially numbered approximately 8,100 men and 110 aircraft. While a sizable force, Akiyama's strength was diluted by the need to spread his command over the entirety of the Marshalls. In addition, many of Akiyama's troops were labor/construction details or naval forces with little ground combat training. As a result, Akiyama could only muster around 4,000 effective. Believing the assault would strike one of the outlying islands first, he positioned the bulk of his men on Jaluit, Mili, Maloelap, and Wotje.

In November 1943, American airstrikes began whittling down Akiyama's airpower, destroying 71 aircraft. These were partially replaced over the next several weeks by reinforcements flown in from Truk. On the Allied side, Admiral Chester Nimitz originally planned a series of assaults on the outer islands of the Marshalls, but upon learning of Japanese troop dispositions through ULTRA radio intercepts altered his approach. Rather than strike where Akiyama's defenses were strongest, Nimitz directed his forces to move against Kwajalein Atoll in the central Marshalls.

Armies & Commanders

Allies

• Rear Admiral Richmond K. Turner
• Major General Holland M. Smith
• approx. 42,000 men (2 divisions)

Japanese

• Rear Admiral Monzo Akiyama
• approx. 8,100 men

Allied Plans

Designated Operation Flintlock, the Allied plan called for Rear Admiral Richmond K. Turner's 5th Amphibious Force to deliver Major General Holland M. Smith's V Amphibious Corps to the atoll where Major General Harry Schmidt's 4th Marine Division would assault the linked islands of Roi-Namur while Major General Charles Corlett's 7th Infantry Division attacked Kwajalein Island. To prepare for the operation, Allied aircraft repeatedly struck Japanese airbases in the Marshalls through December.

This saw B-24 Liberators stage through Baker Island to bomb a variety of strategic targets including the airfield on Mili. Subsequent strikes saw A-24 Banshees and B-25 Mitchells mount several raids across the Marshalls. Moving into position, US carriers began a concerted air offensive against Kwajalein on January 29, 1944. Two days later, US troops captured the small island of Majuro, 220 miles to the southeast, without a fight. This operation was conducted by the V Amphibious Corps Marine Reconnaissance Company and 2nd Battalion, 106th Infantry. 

Coming Ashore

That same day, members of the 7th Infantry Division landed on small islands, dubbed Carlos, Carter, Cecil, and Carlson, near Kwajalein to establish artillery positions for the assault on the island. The next day, the artillery, with additional fire from US warships, including USS Tennessee (BB-43), opened fire on Kwajalein Island. Pummeling the island, the bombardment allowed the 7th Infantry to land and easily overcome the Japanese resistance. The attack was also aided by the weak nature of the Japanese defenses which could not be built in-depth due to the island's narrowness. Fighting continued for four days with the Japanese mounting nightly counterattacks. On February 3, Kwajalein Island was declared secure.

Roi-Namur

At the north end of the atoll, elements of the 4th Marines followed a similar strategy and established firebases on islands dubbed Ivan, Jacob, Albert, Allen, and Abraham. Attacking Roi-Namur on February 1, they succeeded in securing the airfield on Roi that day and eliminated Japanese resistance on Namur the next day. The largest single loss of life in the battle occurred when a Marine threw a satchel charge into a bunker containing torpedo warheads. The resulting blast killed 20 Marines and wounded several others.

Aftermath

The victory at Kwajalein broke a hole through the Japanese outer defenses and was a key step in the Allies' island-hopping campaign. Allied losses in the battle numbered 372 killed and 1,592 wounded. Japanese casualties are estimated at 7,870 killed/wounded and 105 captured. In assessing the outcome at Kwajalein, Allied planners were pleased to find that the tactical changes made after the bloody assault on Tarawa had bore fruit and plans were made to attack Eniwetok Atoll on February 17. For the Japanese, the battle demonstrated that beachline defenses were too vulnerable to attack and that defense-in-depth was necessary if they hoped to stop Allied assaults.