_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.” In the face of the daunting Japanese defenses and the physical constraints of the island, Shoup proposed a landing plan which included a sustained preliminary bombardment, advance seizure of neighboring Bairiki Island as an artillery fire base, and a decoy landing. General Smith took this proposal to the planning conference in Pearl Harbor with the principal officers involved in Operation Galvanic: Admirals Nimitz, Spruance, Turner, and Hill, and Major General Holland Smith. The Marines were stunned to hear the restrictions imposed on their assault by CinCPac. Nimitz declared that the requirement for strategic surprise limited preliminary bombardment of Betio to about three hours on the morning of D-Day. The imperative to concentrate naval forces to defend against a Japanese fleet sortie also ruled out advance seizure of Bairiki and any decoy landings. Then Holland Smith announced his own bombshell: the 6th Marines would be withheld as corps reserve.