Gilbert Islands naval order of battle

Unlike at the Allied landings on Guadalcanal the previous fall, the Japanese chose to violently oppose the Marines on the beach at Betio, the principal island of the Tarawa Atoll.

These extremely well-planned defenses, combined with unexpected tidal conditions, made the fight for Tarawa one of the most difficult for the Marine Corps of the entire Pacific Theater.

Since the Gilberts and Marshalls lie in the Central Pacific, their capture was the responsibility of the U.S. Fifth Fleet, led by Vice Admiral Raymond A. Spruance from aboard his flagship, heavy cruiser USS Indianapolis (CA-35).

In case Admiral Mineichi Koga attempted to disrupt Fifth Fleet's operations, Spruance was to strip all combat ships not needed to cover the landings, join with the fast carrier forces and engage the Japanese.

Unbeknownst to the Americans, the Japanese had stripped almost all their naval and air assets from the Marshalls in an attempt to resist the Allied effort in the Central Solomons.