Map Description

History Map of WWII: Marshall Islands 1943

The Marshall Islands are composed of 29 coral atolls and 5 individual coral islands, forming two roughly parallel island chains known as the Ratak (Sunrise) chain and the Rālik (Sunset) chain. These 29 atolls and 5 islands include over 1,000 individual islands and islets.

The Marshall Islands are widely dispersed across the central Pacific Ocean, spanning over 1.9 million square kilometers (750,000 square miles) of ocean area, though the total land area is only about 181 square kilometers (70 square miles).

Three atolls - Kwajalein, Majuro, and Eniwetok - were directly assaulted and occupied by U.S. forces during WWII.

Four additional atolls - Maloelap, Wotje, Jaluit, and Mili - were attacked by air and sea but not invaded.

The remaining atolls and islands of the Marshall Islands did not see direct battle during WWII.


Illustrating:

Map ⓐ

Northern Kwajalein Atoll: Roi and Namur Islands

4th Marine Division Operations 31 January - 2 February, 1944

As part of Operation Flintlock, the U.S. 4th Marine Division spearheaded the assault on Roi and Namur, twin islands at the northern tip of Kwajalein Atoll, connected by a narrow causeway.

The offensive began on 31 January 1944, with an intense pre-invasion bombardment from naval and aerial forces that devastated Japanese positions. Roi, which hosted an airfield, was lightly defended and fell within six hours on 1 February, following the destruction of most of its infrastructure and aircraft during the bombardment.

Namur, by contrast, presented far stiffer resistance. Japanese troops utilized underground tunnels, bunkers, and strongpoints in a determined defense. The most devastating incident occurred when American forces unknowingly triggered a massive explosion in a torpedo warhead storage bunker. The blast killed 20 Marines and wounded approximately 100 others.

Despite these losses, by 2 February, the island was secured.

U.S. casualties for the operation were reported as 313 killed and 502 wounded. Nearly all of the approximately 3,700 Japanese defenders were killed, with very few taken prisoner.

Note: Some historical sources list 190 killed and 547 wounded for the 4th Marine Division during this operation. The figure of 313 killed is on the higher end of available estimates and may include additional personnel beyond the Marine ground assault forces.

Map ⓑ

Southern Kwajalein Atoll: Kwajalein Island

7th Infantry Division Operations 31 January - 4 February, 1944

While the Marines advanced in the north, the U.S. Army’s 7th Infantry Division landed on Kwajalein Island in the southern part of the atoll.

Beginning on 31 January, 1944, and following days of heavy bombardment, the soldiers encountered formidable Japanese defenses. These included coconut-log bunkers, pillboxes, anti-tank ditches, and minefields that covered much of the island.

The American advance was methodical. Infantry units moved yard by yard with the support of artillery, tanks, and flamethrower teams to clear Japanese positions. Combat often took on an urban character, particularly within the ruins of Japanese barracks and administrative buildings, which provided cover for defenders.

Despite the determined resistance, the 7th Infantry secured the island by 4 February.

Casualties were 177 Americans killed and over 1,000 wounded. Japanese losses were significantly higher — more than 4,900 enemy troops were killed, with only 79 captured alive. The high Japanese fatality rate reflected their adherence to orders to fight to the death rather than surrender.

Strategic Impact

The rapid capture of Kwajalein Atoll in early February 1944 — accomplished in just eight days — demonstrated the effectiveness of the U.S. "island hopping" strategy and highlighted significant improvements in amphibious assault tactics since earlier, more protracted campaigns like the grueling 76-day campaign for Guadalcanal.

Operation FLINTLOCK provided the Allies with a crucial forward base, enabling subsequent advances to Eniwetok (capture of Eniwetok Atoll February 17 to February 23, 1944), and later to the Marianas (Saipan, Tinian, Guam), which would bring American bombers within range of Japan.

Credits

Courtesy of the United States Military Academy Department of History.

Related Links

About the Second World War
WWII Timelines