The elaborate defenses prepared by Admiral Saichiro were impressive. Concrete and steel tetrahedrons, minefields, and long strings of double-apron barbed wire protected beach approaches. The Japanese also built a barrier wall of logs and coral around much of the island. Tank traps protected heavily fortified command bunkers and firing positions inland from the beach. And everywhere there were pillboxes, nearly 500 of them, most fully covered by logs, steel plates and sand.
The Japanese on Betio were equipped with eight-inch, turret-mounted naval rifles (the so-called “Singapore Guns”), as well as a large number of heavy-caliber coast defense, antiaircraft, antiboat, and field artillery guns and howitzers. Dual-purpose 13mm heavy machine guns were prevalent. Light tanks (mounting 37mm guns), 50mm “knee mortars,” and an abundance of 7.7mm light machine guns complemented the defensive weaponry.
LtGen Julian C. Smith Collection
An LVT-1 is lowered from a troop transport during landing rehearsals. Some of the Marines shown here are wearing camouflage utilities while the others are in the usual herringbone twill. Note that the sea appears unusually calm.
The Japanese during August replaced Saichiro with Rear Admiral Meichi Shibasaki, an officer reputed to be more of a fighter than an engineer. American intelligence sources estimated the total strength of the Betio garrison to be 4,800 men, of whom some 2,600 were considered first-rate naval troops. “Imperial Japanese Marines,” Edson told the war correspondents, “the best Tojo’s got.” Edson’s 1st Raider Battalion had sustained 88 casualties in wresting Tulagi from the 3d Kure Special Naval Landing Force the previous August.
Admiral Shibasaki boasted to his troops, “a million Americans couldn’t take Tarawa in 100 years.” His optimism was forgivable. The island was the most heavily defended atoll that ever would be invaded by Allied forces in the Pacific.
Task Force 53 sorely needed detailed tidal information for Tarawa. Colonel Shoup was confident that the LVTs could negotiate the reef at any tide, but he worried about the remainder of the assault troops, tanks, artillery, and reserve forces that would have to come ashore in Higgins boats (LCVPs). The critical water depth over the reef was four feet, enough to float a laden LCVP. Anything less and the troops would have to wade ashore several hundred yards against that panoply of Japanese weapons.
Major Frank Holland, a New Zealand reserve officer with 15 years’ experience sailing the waters of Tarawa, flatly predicted, “there won’t be three feet of water on the reef!” Shoup took Holland’s warnings seriously and made sure the troops knew in advance that “there was a 50-50 chance of having to wade ashore.”