Battle of Tarawa
The Battle of Tarawa, or Operation GALVANIC, took place in November 1943 when U.S Marines of the 2nd Marine Division captured the island of Betio in the Tarawa atoll of the Gilbert Islands. Secondary attacks took Makin (Operation KOURBASH) and Apamama (Operation BOXCLOTH) Islands. Naval support came from the United States Fifth Fleet.
2nd Marine Regiment was designated the assault force. Its commander Colonel William McN. Marshall, became ill during rehearsals. Major General Julian Smith, divisional commander, replaced him with Col. David Shoup the division's plans and operations officer. "Thus, Shoup was placed in the unusual position of now being called upon to execute orders based upon planning in which he had had a major part."  Shoup was to receive the Medal of Honor for his leadership, and would later become Commandant of the Marine Corps.
While they overwhelmed the 4,500-strong Japanese garrison, American casualties were high. A major factor was lack of current intelligence on the unusual tidal patterns of the area, as well as depths of the surrounding reefs. Marines had to wade, under fire, through deep water. Once they reached the beach, they were both pinned down and protected by a seawall.
Lessons learned helped the allies to improve the techniques of amphibious warfare, learning from their mistakes and implementing changes such as thorough pre-emptive bombings and bombardment, more careful planning regarding tides and landing craft schedules, and better overall coordination.