The Gilbert and Marshall Islands campaign was a series of engagements fought from August 1942 to February 1944, in the Pacific theatre of

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

between the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

and

Japan Japan is an island country in East Asia. Located in the Pacific Ocean off the northeast coast of the Asia, Asian mainland, it is bordered on the west by the Sea of Japan and extends from the Sea of Okhotsk in the north to the East China Sea ...

. They were the first battles of a large-scale offensive across the Central Pacific by the

United States Pacific Fleet The United States Pacific Fleet (USPACFLT) is a theater-level component command of the United States Navy, located in the Pacific Ocean. It provides naval forces to the Indo-Pacific Command. Fleet headquarters is at Joint Base Pearl Harbor� ...

and

Marine Corps Marines (or naval infantry) are military personnel generally trained to operate on both land and sea, with a particular focus on amphibious warfare. Historically, the main tasks undertaken by marines have included raiding ashore (often in supp ...

. The goal of the campaign was to establish airfields and naval bases that would allow American air and naval assets to support future operations across the Central Pacific. Operation ''Galvanic'' and Operation ''Kourbash'' were the codenames for the

Gilberts The Gilbert Islands (;Reilly Ridgell. ''Pacific Nations and Territories: The Islands of Micronesia, Melanesia, and Polynesia.'' 3rd. Ed. Honolulu: Bess Press, 1995. p. 95. formerly Kingsmill or King's-Mill IslandsVery often, this name applied o ...

campaign (in modern

Kiribati Kiribati, officially the Republic of Kiribati, is an island country in the Micronesia subregion of Oceania in the central Pacific Ocean. Its permanent population is over 119,000 as of the 2020 census, and more than half live on Tarawa. The st ...

), and included the seizures of

Tarawa Tarawa is an atoll and the capital of the Republic of Kiribati,Kiribati
''

Makin, which took place during the

Battle of Tarawa The Battle of Tarawa was fought on 20–23 November 1943 between the United States and Japan on Tarawa Atoll in the Gilbert Islands, and was part of Operation Galvanic, the U.S. invasion of the Gilberts. Nearly 6,400 Japanese, Koreans, and Am ...

on 20–23 November 1943 and the

Battle of Makin A battle is an occurrence of combat in warfare between opposing military units of any number or size. A war usually consists of multiple battles. In general, a battle is a military engagement that is well defined in duration, area, and force ...

on 20–24 November 1943. Operation ''Flintlock'' and Operation ''Catchpole'' had the goal of capturing Japanese bases at Kwajalein,

Eniwetok Enewetak Atoll (; also spelled Eniwetok Atoll or sometimes Eniewetok; , , or , ; known to the Japanese as Brown Atoll or Brown Island; ) is a large coral atoll of 40 islands in the Pacific Ocean and with its 296 people (as of 2021) forms a legi ...

, and

Majuro Majuro (; Marshallese language, Marshallese: ' ) is the Capital city, capital and largest city of the Marshall Islands. It is also a large coral atoll of 64 islands in the Pacific Ocean. It forms a legislative district of the Ratak Chain, Ratak ( ...

in the

Marshall Islands The Marshall Islands, officially the Republic of the Marshall Islands, is an island country west of the International Date Line and north of the equator in the Micronesia region of the Northwestern Pacific Ocean. The territory consists of 29 c ...

Background

The

Imperial Japanese Navy The Imperial Japanese Navy (IJN; Kyūjitai: Shinjitai: ' 'Navy of the Greater Japanese Empire', or ''Nippon Kaigun'', 'Japanese Navy') was the navy of the Empire of Japan from 1868 to 1945, Potsdam Declaration, when it was dissolved followin ...

occupied the

Gilbert Islands The Gilbert Islands (;Reilly Ridgell. ''Pacific Nations and Territories: The Islands of Micronesia, Melanesia, and Polynesia.'' 3rd. Ed. Honolulu: Bess Press, 1995. p. 95. formerly Kingsmill or King's-Mill IslandsVery often, this name applied o ...

three days after the

attack on Pearl Harbor The attack on Pearl HarborAlso known as the Battle of Pearl Harbor was a surprise military strike by the Empire of Japan on the United States Pacific Fleet at Naval Station Pearl Harbor, its naval base at Pearl Harbor on Oahu, Territory of ...

. The Japanese built a seaplane base on Makin and dispersed troops along the coastlines of the northern atolls to monitor the Allied forces' movement in the

South Pacific The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...

. The

are located approximately 220 miles (350 km) northwest of the Gilbert Islands, and had been occupied by the Japanese since

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

as part of the

South Seas Mandate The South Seas Mandate, officially the Mandate for the German Possessions in the Pacific Ocean Lying North of the Equator, was a League of Nations mandate in the " South Seas" given to the Empire of Japan by the League of Nations following W ...

. The Japanese regarded the islands as an important outpost for their navy. Allied commanders believed that an eventual surrender of Japan would require the capture of these islands. While General

Douglas MacArthur Douglas MacArthur (26 January 18805 April 1964) was an American general who served as a top commander during World War II and the Korean War, achieving the rank of General of the Army (United States), General of the Army. He served with dis ...

, commander of the

United States Army The United States Army (USA) is the primary Land warfare, land service branch of the United States Department of Defense. It is designated as the Army of the United States in the United States Constitution.Article II, section 2, clause 1 of th ...

in the south Pacific, wanted to push towards the

Philippines The Philippines, officially the Republic of the Philippines, is an Archipelagic state, archipelagic country in Southeast Asia. Located in the western Pacific Ocean, it consists of List of islands of the Philippines, 7,641 islands, with a tot ...

via

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; , fossilized , also known as Papua or historically ) is the List of islands by area, world's second-largest island, with an area of . Located in Melanesia in the southwestern Pacific Ocean, the island is ...

United States Navy The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...

Admiral

Chester W. Nimitz Chester William Nimitz (; 24 February 1885 – 20 February 1966) was a fleet admiral in the United States Navy. He played a major role in the naval history of World War II as Commander in Chief, US Pacific Fleet, and Commander in Chief, ...

favored a drive across the Central Pacific,

leapfrogging Leapfrogging is a concept used in many domains of the economics and business fields, and was originally developed in the area of industrial organization and economic growth. The main idea behind the concept of leapfrogging is that small and incre ...

through the Gilberts, the Marshalls, the Carolines, and the

Marianas The Mariana Islands ( ; ), also simply the Marianas, are a crescent-shaped archipelago comprising the summits of fifteen longitudinally oriented, mostly Volcano#Dormant and reactivated, dormant volcanic mountains in the northwestern Pacific Ocean ...

. This would place American

B-29 The Boeing B-29 Superfortress is a retired American four-engined Propeller (aeronautics), propeller-driven heavy bomber, designed by Boeing and flown primarily by the United States during World War II and the Korean War. Named in allusion to ...

bombers within range of

Tokyo Tokyo, officially the Tokyo Metropolis, is the capital of Japan, capital and List of cities in Japan, most populous city in Japan. With a population of over 14 million in the city proper in 2023, it is List of largest cities, one of the most ...

. In addition to forcing the Japanese to fight two fronts against the Allies ( Nimitz driving from the east and MacArthur from the south), Nimitz's plan would neutralize important outlying Japanese defenses and provide bases American forces to conduct future attacks against Japanese-occupied islands. The plan called for the seizure of Tarawa and Makin in the Gilbert Islands, and Majuro, Kwajalein, and Eniwetok in the Marshalls.

Gilberts

Prelude

Japanese forces occupied the Gilbert Islands on 9-10 December 1941, landing troops of the

South Seas Detachment The of the Imperial Japanese Army was a brigade-size force formed in 1941 to be the army unit used in the Japanese seizure of the South Pacific island groups of Wake, Guam and the Gilberts. As part of the South Seas Force, it fell under Imperi ...

Tarawa Tarawa is an atoll and the capital of the Republic of Kiribati,Kiribati
''

Butaritari Butaritari is an atoll in the Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on th ...

and Makin), a few days after the attack on Pearl Harbor. These forces were tasked with protecting the southeastern Japanese flank from Allied counterattacks, and with isolating Australia. The islands were designated as a staging point for the planned invasion of the

Ellice Islands Tuvalu ( ) is an island country in the Polynesian subregion of Oceania in the Pacific Ocean, about midway between Hawaii and Australia. It lies east-northeast of the Santa Cruz Islands (which belong to the Solomon Islands), northeast of Van ...

during

Operation FS __NOTOC__ Operation FS was the Imperial Japanese plan to invade and occupy Fiji, American Samoa, Samoa, and New Caledonia in the South Pacific during the Pacific conflict of World War II. The operation was set to be executed in July or August 19 ...

, but the Japanese setback at the

Coral Sea The Coral Sea () is a marginal sea of the Pacific Ocean, South Pacific off the northeast coast of Australia, and classified as an Interim Biogeographic Regionalisation for Australia, interim Australian bioregion. The Coral Sea extends down t ...

delayed these plans, and their defeats at Midway and later in the

Guadalcanal campaign The Guadalcanal campaign, also known as the Battle of Guadalcanal and codenamed Operation Watchtower by the United States, was an Allies of World War II, Allied offensive against forces of the Empire of Japan in the Solomon Islands during th ...

put a definitive end to an offensive utilization of the islands by the Japanese. Following Carlson's Raiders' diversionary

raid on Makin Island The raid on Makin Island was an attack by Marine Raiders of the United States Marine Corps on the Japanese-controlled Makin Island from August 17–18, 1942. Aims of the raid included destroying local installations, acquiring prisoners of war ...

and the defeat at

Guadalcanal Guadalcanal (; indigenous name: ''Isatabu'') is the principal island in Guadalcanal Province of Solomon Islands, located in the southwestern Pacific Ocean, northeast of Australia. It is the largest island in the Solomons by area and the second- ...

, the Japanese command had grown aware of the vulnerability and strategic significance of the Gilbert Islands, and started adopting a defensive stance. Because Japanese planners wanted to heavily fortify the Marianas and Palau before the Americans could arrive there in force, garrison commanders in the outer islands were told to hold out as long as possible with minimal support. Fortifications were quickly improved by the Japanese beginning in March 1943. Makin Atoll had a seaplane base built on the main island of Butaritari, while Tarawa housed barely enough room for an airfield on its main harbor island,

Betio Betio is the name of both an island and a township within the Tarawa Atoll, part of the Republic of Kiribati. Betio is the largest township of Kiribati's capital city, South Tarawa, and it is also the country's primary port. Betio is located on ...

Battle of Tarawa

American forces seized Tarawa from nearly 5,000 Imperial Japanese Naval Landing Forces (3,000

Special Naval Landing Forces The Special Naval Landing Forces (SNLF; ) were standalone naval infantry units in the Imperial Japanese Navy (IJN) and were a part of the IJN land forces. They saw extensive service in the Second Sino-Japanese War and in the Pacific theatre o ...

and 1,247 construction laborers) from 20-23 November 1943. The Makin Islands, in contrast, were only held by a total of 798 Japanese troops, including some 100 isolated Japanese aviation personnel. A detachment of 300 soldiers from Tarawa also occupied the island of

Abemama Abemama (Apamama) is an atoll, one of the Gilberts group in Kiribati, and is located southeast of Tarawa and just north of the Equator. Abemama has an area of and a population of 3,299 . The islets surround a deep lagoon. The eastern part of ...

in September 1942, but by the time American troops landed there in November 1943, most Japanese soldiers had been evacuated back to Tarawa, leaving only 25 Special Naval Landing Forces behind to defend the island. Lieutenant Junior Grade Seizo Ishikawa, the Japanese commander in charge of defending Makin, ordered his troops to build extensive fortifications on the island. These included several coastal defense guns, anti-tank gun positions, machine gun emplacements, rifle pits, and deep tank barriers with anti-tank guns and barbed wire. These were ostensibly designed to hold the island until reinforcements could arrive. On Tarawa,

Keiji Shibazaki was a Rear Admiral in the Imperial Japanese Navy. He was the commander of the Japanese garrison on the island of Betio of the Tarawa atoll during World War II. Shibazaki and all his senior officers were killed by naval gunfire on the first day ...

had 4,836 troops, including around 2,600 Special Naval Landing Forces, 1,000 Japanese construction workers and 1,200 Korean laborers. He intended to primarily defend Betio, the largest island in the atoll and the site of a crucial Japanese airfield. Shibazaki had 14 coastal defense guns, 50 pieces of field artillery at his dispoal, and oversaw the construction of over 100 machine gun nests, 500 pillboxes, and a large wall across the northern lagoon. Despite heavy casualties, the U.S. Marines took Tarawa after 3 days of fighting. Many officers questioned the significance of the invasion and accompanying heavy loss of American lives.

Marshalls

Prelude

After the Gilbert Islands fell to the Americans in late November 1943, Admiral

Mineichi Koga was a Japanese Marshal Admiral and commander-in-chief of the Imperial Japanese Navy's Combined Fleet. Biography Early life and career Koga was born in the ceramics center of Arita in Nishimatsuura County of Saga Prefecture in 1885. He ente ...

of the Japanese Combined Fleet was unsure of which islands the Americans would strike next. Without any carrier aircraft to provide reconnaissance, he ordered Admiral Masami Kobayashi to disperse his 28,000 troops primarily to the outer islands of Maloelap,

Wotje Wotje Atoll ( Marshallese: , ) is a coral atoll of 75 islands in the Pacific Ocean, and forms a legislative district of the Ratak Chain of the Marshall Islands. Geography Wotje's land area of is one of the largest in the Marshall Islands, and ...

, Jaliuit, and Mili. However, Allied intelligence intercepted and decrypted the Japanese transmissions, informing the Americans which islands were more heavily defended. The Americans therefore decided to invade the lesser-protected but strategically important islands of

, Kwajalein, and

. As early as November 1943, B-24 bombers from the

Seventh Air Force The Seventh Air Force (Air Forces Korea) (7 AF) is a Numbered Air Force of the United States Pacific Air Forces (PACAF). It is headquartered at Osan Air Base, South Korea. The command's mission is to plan and direct air component operations in ...

stationed in the Ellice Islands had flown bombing missions over Mili and Maloelap. On 3 December 1943,

Task Force A task force (TF) is a unit or formation established to work on a single defined task or activity. Originally introduced by the United States Navy, the term has now caught on for general usage and is a standard part of NATO terminology. Many ...

50, under Rear Admiral Charles Alan Pownall, including fleet carriers , , , and and light carriers and , launched airstrikes against Kwajalein. Four transports were sunk and fifty Japanese aircraft were destroyed, but the attack lacked strategic value. Fearing a counterattack from Wotje, Pownall ordered a second strike against the island. The Japanese counterattacked in a night bombing raid, in which ''Lexington'' sustained a torpedo hit but was not sunk. The American task force later returned to Pearl Harbor. The ''Yorktown''s aircraft would continue to fly air cover over the atoll on 29 January, 31 January, and from 1 to 3 February. The invasion of the Marshalls was delayed for about a month due to logistical problems. Japanese commander Rear Admiral

Monzo Akiyama Monzo Bank Limited, trading as Monzo (), is a British online bank based in London, England. Monzo launched as part of a wave of app-based challenger banks entering the UK market. Originally operating through a mobile app and a prepaid debi ...

was aware that he lacked sufficient fortifications. He commanded a garrison of 8,000 men, but only about half of them were soldiers; most of the rest were Korean laborers. To defend Kwajalein, Akiyama was relying on an aerial counterstrike with his 110 aircraft to weaken the American landing forces. However, on 29 January 1944, American carrier aircraft from carriers ''Yorktown'', ''Lexington'', and ''Cowpens'' destroyed 92 Japanese fighters and bombers on the island. Akiyama now lacked the ability to effectively mount a successful defense of the island.

Battle of Majuro

On 31 January 1944, Rear Admiral Harry W. Hill dispatched the Reconnaissance Company from the

V Amphibious Corps The V Amphibious Corps (VAC) was a formation of the United States Marine Corps which was composed of the 3rd, 4th and 5th Marine Divisions in World War II. The three divisions were the amphibious landing force for the United States Fifth Fl ...

of the U.S. Marines and the U.S. Army's 2nd Battalion, 106th Infantry, 27th Infantry Division to land on Majuro. This marked the beginning of Operation Flintlock, the invasion of Kwajalein. American planners viewed the island as an important base for conducting air operations against the rest of the Marshall Islands, and eventually the Marianas. The force took the lightly defended island in a single day without any casualties.

Battle of Kwajalein

The same day as the landings on Majuro, the

4th Marine Division The 4th Marine Division is a reserve division in the United States Marine Corps. It was raised in 1943 for service during World War II, and subsequently fought in the Pacific against the Japanese. Deactivated after the war, the division was re ...

under Major General Harry Schmidt began their assault on Kwajalein. The Marines first landed on

Roi-Namur Roi-Namur ( ) is an island in the north part of the Kwajalein Atoll in the Marshall Islands. Today, the island is a major part of the Ronald Reagan Ballistic Missile Defense Test Site, hosting several radar systems used for tracking and character ...

, a group of islands in the northern part of the atoll. Significant confusion and delays were caused by poor weather and inexperienced Marines, but the pre-invasion naval and air bombardment was extremely effective. Out of roughly 3,000 Japanese soldiers, only about 300 were left to contest the American landings. On the southern island of Kwajalein, Major General Charles H. Corlett's 7th Infantry Division landed with relative ease. Although Japanese defensive fortifications and counterattacks slowed the Americans, more troops, more experience in amphibious landings, an effective pre-landing bombardment, and the position of Japanese defenses on the opposite side of the atoll from where the Americans landed contributed to the capture of Kwajalein and its surrounding islands on 7 February. Of the entire force of about 8,000 Japanese troops guarding Majuro and Kwajalein, only 253 were taken prisoner. The Americans suffered 348 men killed, 1,462 wounded, and 183 missing in the eight days it took to take the atoll.

Battle of Eniwetok

American strategists believed that Eniwetok's islets contained enough room for airfields deemed critical for the upcoming invasion of the Marianas. Japanese Major General Yoshimi Nishida knew that it would be difficult to hold the main island of Eniwetok against invasion. He had roughly 4,000 troops, half of them IJA troops, the remainder a variety of sailors. Since the Americans would be landing with naval and air support, therefore giving them the upper hand once they established a beachhead, he decided to attempt to stop them at the beaches. On 17 February 1944 the American naval bombardment of Eniwetok Atoll began, marking the beginning of Operation Catchpole. The same day, the 22nd Marine Regiment under Colonel John T. Walker landed on the northern island of Engebi. The landings were a logistically difficult, with American men and materiel scattered along the beach. The Marines took the island on 18 February with 85 dead and 166 wounded. On 19 February, the 106th Infantry Regiment, under Lieutenant General Thomas E. Watson, landed on the main island of Eniwetok after a heavy bombardment. However, the Japanese

spider hole Illustration of a spider hole In military slang, a spider hole is a type of camouflaged one-man foxhole, similar to a surveillance/hidesite used for observation. Etymology The term is usually understood to be an allusion to the camouflaged h ...

s and

bunker A bunker is a defensive military fortification designed to protect people and valued materials from falling bombs, artillery, or other attacks. Bunkers are almost always underground, in contrast to blockhouses which are mostly above ground. T ...

s withstood much American shore bombardment. Landing American troops also faced the same logistical problems as the 22nd Marine Regiment on Engebi. Japanese forces concentrated in the southwest corner of the island counterattacked the American flank, forcing the Americans to attack mainly at night. Eniwetok Island was captured on 21 February with the loss of 37 Americans and nearly 800 Japanese. On Parry Island, the Americans used heavy gunfire support from battleships before the 22nd Marine Regiment, under Watson, came ashore on 22 February, capturing the entire atoll by 23 February. On Eniwetok, 313 Americans were killed in the fighting, 879 were wounded, and 77 were reported missing, while the Japanese suffered 3,380 dead and 105 captured. This marked an end to the Marshall Islands campaign.

Aftermath

The Americans emerged victorious in the Gilbert Islands campaign but suffered from logistical and experiential mishaps, ultimately incurring a total of 2,459 dead and 2,286 wounded. Meanwhile, Japanese forces suffered a total of 5,085 dead and 247 captured. The heavy casualties and gruesome fighting conditions for both sides convinced General

Holland Smith Holland McTyeire "Howlin' Mad" Smith, Order of the Bath, KCB (April 20, 1882 – January 12, 1967) was a General officer, general in the United States Marine Corps during World War II. He is sometimes called the "father" of modern United St ...

, commanding general of V Amphibious Corps, that Tarawa should have been bypassed, although other high-ranking American officers disagreed.Smith, Holland M.; Finch, Perry (1976). ''Coral and Brass.'' New York, NY: Viking. By contrast, the Marshall Islands fell to American forces with relative ease. The Americans used lessons learned at Tarawa by ensuring that they outnumbered enemy defenders by nearly 6 to 1, and brought heavier firepower to bear (including use of armor-piercing shells), even after the islands had received nearly a month of heavy air and naval bombardment. In the Marshalls, the Americans had 611 killed, 2,341 wounded, and 260 missing, while the Japanese lost over 11,000 men and had 358 captured. After the Gilbert and Marshall Islands were taken, the Allies built naval bases, fortifications, and airfields on the islands to prepare for an assault on the Marianas. The Japanese defeat forced the IJA and IJN to draw back to a new defensive perimeter, the Absolute National Defense Zone, which included the

and

Palau Palau, officially the Republic of Palau, is an island country in the Micronesia subregion of Oceania in the western Pacific Ocean. The Republic of Palau consists of approximately 340 islands and is the western part of the Caroline Islands ...

. Japanese forces heavily fortified these islands against the impending American assault, because if captured, they would allow American heavy bombers to directly target the Japanese home islands.

Background

Gilberts

Prelude

Battle of Tarawa

Marshalls

Prelude

Battle of Majuro

Battle of Kwajalein

Battle of Eniwetok

Aftermath

See also

References

Further reading