Order of Battle
After the brief assault by Carlson's Raiders on Makin (northern Gilbert Islands) in August 1942, the Japanese realized the vulnerability of their positions in the Gilberts.
Soon after this raid, Admiral Saichiro (who was in charge of Japanese troops in the Gilberts until August 1943) decided to fortify Betio and make of it one of the most heavily-defended islands of the Pacific.
The fortifications consisted of "concrete and steel tetrahedrons, minefields, and long strings of double-apron barbed wire [...]. Tank traps protected heavily fortified command bunkers and firing positions[...]" (Alexander, p.3).
Five hundred pillboxes, artillery emplacements, machinegun nests, bunkers and other defenses were built, and a wall made of coconut logs and coral was built around much of the island to prevent tanks from going inland.
In addition to those static defenses, a contingent of seven type 95 Ha-Go light tanks gave the Japanese mobile fire power.
By September 1943, the Japanese garrison on Betio consisted of the 7th Sasebo SNLF (Special Naval Landing Force), the 3rd Special Base Force, the 111th Pioneers and the 4th Construction Unit.
According to the American intelligence, about 4,800 men comprised this garrison.
Ideally, this plan was supposed to annihilate the American forces on the beaches. In addition, the fortifications on the island were intended to buy time for the Imperial Fleet to destroy the American forces in their ships.
"The goal of the defense was to delay the enemy and buy time to launch a naval Yogaki or 'waylaying attack' ". (Gilbert, p. 78).
Admiral Keichi Shibasaki, who replaced Admiral Saichiro, declared: "a million men could not take Tarawa in a hundred years"...
Admiral Nimitz, in charge of the Pacific fleet, knew about the Japanese Yogaki plan, and instructed the commander of the Task Force 53, Vice Admiral Raymond Spruance, to attack Betio and have his vulnerable ships leave the place as soon as possible.
The assault troops were composed by five infantry battalions of the 2nd Marine Division, commanded by General Julian Smith. Those troops were supported by an artillery battalion, the Scout Sniper Platoon and the composite 2nd Tank Battalion.
Altogether, more than 18 000 Marines and sailors took part in the Tarawa assault.
For the first time, medium tanks were to be employed in support of a landing assault. Until now, their use was limited both "by the Army's demand for tanks, and by problems of how transport and land such heavy vehicles".
By 1943, "the Marines could procure only diesel-powered M4A2s, a model the Army would not accept for overseas service".
In fact, "the Army cited reliability and high maintenance burdens as objections to the diesel engine, but the Marines did not find either to be a problem". (Gilbert p. 79).
Soon after this raid, Admiral Saichiro (who was in charge of Japanese troops in the Gilberts until August 1943) decided to fortify Betio and make of it one of the most heavily-defended islands of the Pacific.
The fortifications consisted of "concrete and steel tetrahedrons, minefields, and long strings of double-apron barbed wire [...]. Tank traps protected heavily fortified command bunkers and firing positions[...]" (Alexander, p.3).
Five hundred pillboxes, artillery emplacements, machinegun nests, bunkers and other defenses were built, and a wall made of coconut logs and coral was built around much of the island to prevent tanks from going inland.
In addition to those static defenses, a contingent of seven type 95 Ha-Go light tanks gave the Japanese mobile fire power.
By September 1943, the Japanese garrison on Betio consisted of the 7th Sasebo SNLF (Special Naval Landing Force), the 3rd Special Base Force, the 111th Pioneers and the 4th Construction Unit.
According to the American intelligence, about 4,800 men comprised this garrison.
Ideally, this plan was supposed to annihilate the American forces on the beaches. In addition, the fortifications on the island were intended to buy time for the Imperial Fleet to destroy the American forces in their ships.
"The goal of the defense was to delay the enemy and buy time to launch a naval Yogaki or 'waylaying attack' ". (Gilbert, p. 78).
Admiral Keichi Shibasaki, who replaced Admiral Saichiro, declared: "a million men could not take Tarawa in a hundred years"...
Admiral Nimitz, in charge of the Pacific fleet, knew about the Japanese Yogaki plan, and instructed the commander of the Task Force 53, Vice Admiral Raymond Spruance, to attack Betio and have his vulnerable ships leave the place as soon as possible.
The assault troops were composed by five infantry battalions of the 2nd Marine Division, commanded by General Julian Smith. Those troops were supported by an artillery battalion, the Scout Sniper Platoon and the composite 2nd Tank Battalion.
Altogether, more than 18 000 Marines and sailors took part in the Tarawa assault.
For the first time, medium tanks were to be employed in support of a landing assault. Until now, their use was limited both "by the Army's demand for tanks, and by problems of how transport and land such heavy vehicles".
By 1943, "the Marines could procure only diesel-powered M4A2s, a model the Army would not accept for overseas service".
In fact, "the Army cited reliability and high maintenance burdens as objections to the diesel engine, but the Marines did not find either to be a problem". (Gilbert p. 79).
Gilbert Island Chain
THE ISLAND CHAIN, TARAWA.
American forces would attack several islands in the Gilbert Islands chain. The Army would attack the older Japanese bases at Butaritari and Makin, while the Marine Corps operation would focus on Tarawa Atoll. (An atoll is a ring of islands formed around an extinct volcano that has sunk below sea-level.)
The Marines would assault the extreme southwestern island, Bititu, the only island suitable for an airfield, and the site of an existing Japanese airbase.
On these first two maps, the name of the target island is spelled Bititu, but it is more commonly spelled and known as Betio. It will be identified by this latter spelling in most places here, to avoid possible confusion.
Maps of Betio.
Source: Archives and Special Collections; Library of the Marine Corps.
This is a 1943 situation map of Betio, and the landing beaches are all identified with their code names.The Japanese had expected an attack on the Black (seaward) Beaches, and they were the most heavily fortified. The American planners decided to enter the lagoon and attack from the RED Beaches.
Bititu is a tiny island, and its widest point is less than 700 yards (640 m) across and is about 1.75 miles (2.8 km) long.
This map shows the military details as they were known at the time. The sketchy outline off the island shows the general location of the reefs which would later have a great impact upon the landings.
Bititu is a tiny island, and its widest point is less than 700 yards (640 m) across and is about 1.75 miles (2.8 km) long.
This map shows the military details as they were known at the time. The sketchy outline off the island shows the general location of the reefs which would later have a great impact upon the landings.
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Detailed map of Betio. Source: Archives and Special Collections Library of the Marine Corps.
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