On 20 November 1943, the Second Marine Division assaulted Betio (BAY-shio) Island in the Tarawa Atoll of the Gilbert Islands, at that time a British Protectorate, located in the Central Pacific a little northwest of the point where the Equator crosses the International Dateline. Betio is two miles long by a half-mile wide, 291 acres, less than half the size of New York City's Central Park.
The object of the assault was a Japanese airfield which Admiral Nimitz felt would hinder the upcoming island-hopping campaign which would provide stepping stones toward Japan for airfields and supply bases. The island was heavily fortified. There were 2700 Rikusentai, Japanese Naval Infantry much like our Marines, 1000 Japanese construction workers, and 1200 Korean laborers. U.S. Intelligence calculated the number of personnel quite accurately by analyzing the number of privies in aerial reconnaisance photos.
The Japanese commander, Admiral Shibasaki, claimed that "a million men could not take Tarawa in a hundred years".
The Marines were to assault from the lagoon side of Betio rather than the seaward side, to avoid Japanese coastal guns sited in that direction. They would have to cross a reef to do so. The only maps available were U.S. Naval maps drawn by an expedition in 1841. Former British planters provided information about tides, crucial because the assault boats needed at least 3 1/2 feet of water over the reef to clear it. The Brits estimated 4 to 5 feet of depth at that time of year, but warned that they might be off by a foot or so due to unusual 'dodging' tides. U.S. planners went by the estimate and were dead ass wrong.
Prior to the assault, U.S. Navy ships and planes bombed and shelled Betio with 3000 tons of high explosives, or over ten tons per acre. Since the island was very flat, a lot of low-angle ordnance skipped off into the ocean. The Jap fortifications, some with walls eight feet thick, were damaged but their occupants survived and came out ready to fight. Their communications were disrupted, but the defending force was pretty much intact.
The first wave came ashore in amphibious tractors, 'Alligators', and the following waves came in Higgins boats. There was not enough water over the reef and the boats were stopped, so a shuttle began from the boats to the beach by returning Alligators. They had started with only 125 of these and almost half were knocked out in the first wave. The Japs had over 100 machine guns and several anti-boat guns facing the lagoon. Many Marines disembarked and waded ashore in chest-deep water for over 500 yards. Many were killed by Jap fire, and many stepped in holes and drowned.
Once ashore, the Marines were pinned down on the beach behind a log sea-wall. Radios were shot up or soaked. Command and control was lost due to casualties, units landing on the wrong part of the beach, general confusion, and the 'fog of war'. Finally, junior officers, NCO's, even buck privates, began to take charge, organizing small groups of men and assaulting over the sea-wall toward the airfield, which at one end was only 50 yards from the beach. The fighting was mostly with grenades, flamethrowers and demolition charges. The Japs had an extensive bunker system, interconnected by trenches and tunnels. It was slow, deadly work, one bunker at a time, each one supported by fires from others.
The highest point on Betio was a bombproof bunker. Marines gained its top at great cost. They threw grenades down the vent pipe and shot many Japs at point-blank range as they poured out the back doors. They dealt with survivors by pouring gasoline down the vents, followed by satchel charges. Later, they counted 200 charred corpses in the bombproof.
The assault force commander, Colonel David M. Shoup, who received the Medal Of Honor for this action and was the Commandant of the Marine Corps in the sixties when I was a Marine, at one point sent this message: "Casualties: many. Percentage dead: unknown. Combat efficiency: we are winning."
The battle raged for three days and Betio was declared secured after 76 hours. The Marines lost over 1000 KIA and 2300 WIA. 17 Japs and 123 Koreans survived out of 4900. It was the fiercest, most hard-fought and bloody battle the Marines had been in up to that time. Picture 15,000 armed men in half of Central Park, each trying to kill the other by whatever means, and you get the idea.
This was the first assault against a heavily fortified beach in the Pacific War. Many lessons were learned. Naval gunfire was modified to use high-angle fire which would come down on a target instead of skipping off. Pin-point fire was used instead of saturation fire. Combat swimmers were trained to gather intelligence about tides and beaches. It cost a lot of lives to learn these lessons, but many lives were later saved.
Ironically, the Jap fortifications that resulted in so many Marine casualties resulted from an earlier Marine success. In late 1942, Colonel Evans F. Carlson's 2d Raider Battalion had assaulted Makin Island which was in the Gilberts about 100 miles north of Betio. They kicked ass. Forewarned being forearmed, the Japs fortified the shit out of Betio.
The movie Gung Ho with Randolph Scott was the Hollywood version of the Makin raid, but does not mention the nine Marines who were inadvertently left behind and later beheaded. The Jap who did that was executed for it after the war and the bodies were only recovered a couple of years ago.
Today, the former Gilbert Islands are the independent Republic of Kiribati.
My source was: Time-Life series World War Two: Island fighting. You can read and see more at Tarawa on the Web.