Pvt. Albert Gilman readied his weapon as an amphibious vehicle carried him and 20 other Marines closer to their Pacific island objective. They were going to hit the beach with the first wave. Their superiors had assured them that the operation that day - Nov. 20, 1943 - would be easy.
Gilman noticed little to challenge that prediction as the vehicle approached the shore. Naval and air bombardments had so denuded the palm trees they resembled fence posts to the young private.
"At that instant, there was little fear," he says. "Then, suddenly, all hell broke loose."
Heavily fortified bunkers had helped most Japanese defenders survive the powerful pre-invasion bombardment. Now they poured an ever-increasing volume of fire into the surprised Marines. A normally placid lagoon became a cauldron of dying men. Gilman and the other members of the initial wave had experienced their first taste of warfare on Tarawa - an island, one Marine said, "whose very name evokes terror."
Tarawa Atoll is part of the Gilbert Islands, which straddle the equator about 2,500 miles southwest of Hawaii. It is an idyllic, triangular atoll of 25 small isles. A jagged coral reef surrounding Tarawa poses an ominous threat to anyone approaching it.
U.S. military strategists coveted Betio, the largest of Tarawa's isles, because it contained an enemy airfield threatening lines of communication between Australia and the United States.
Adm. Raymond A. Spruance, the quiet, modest man who defeated the Japanese in the crucial Battle of Midway, was placed in command of the Gilbert invasion, code-named "Galvanic." Spruance decided to approach Betio from its lagoon side. The Marines would hit three connecting beaches on the isle, capture the airfield, then advance straight across Betio to split Japanese forces in two.
The operation's quickness and relative ease depended on sufficient water over the reef - about 700 yards from shore - to allow all landing boats passage. If there was not enough water, only Marines of the first three waves, using smaller and more agile amphibious tractors, or amtracs, could get over the reef. These men, including Gilman, would be stranded on the beach, waiting for reinforcements to wade through neck-deep water.
Military leaders felt the invasion would take only a few hours. Rear Adm. Harry W. Hill, Southern Force commander, predicted that "we're going to steam-roller that place until hell wouldn't have it."
Rear Adm. Keiji Shibasaki, Japanese commander at Tarawa, predicted a different outcome, for good reason. His 4,500-strong special naval landing force had crafted underwater obstacles to channel attacking Marines into deadly point-blank range. A 3- to 5-foot sea wall, built with coconut tree logs, would block any Marine who made it across the beach. Once ashore, Marines faced Japanese mortars and machine guns that covered every foot of sand. Shibasaki had built a killing field.
He could employ 200 heavy guns, ranging from machine guns to 8-inch cannon. He camouflaged them in hexagon-shaped pillboxes of double-tiered logs, hooked together with railroad spikes. Shibasaki positioned the pillboxes so that each would be safe from all but a direct hit from a large shell, boasting, "A million men cannot take Tarawa in 100 years."
At 2:50 a.m., Betio was sighted, and within the hour Gilman joined other first-wave Marines climbing down nets into landing craft. Shortly after 5 a.m., 15 U.S. warships unleashed their powerful salvos against the enemy, and the battle was on.
The Firestorm. In three hours, 10 tons of shells hit every acre of the isle in the most intense pre-invasion bombardment in naval history. It inflicted little damage on the Japanese, but Shibasaki's communications were knocked out, making tactical coordination practically impossible.
The first three waves of 94 amtracs and 1,500 Marines churned toward one of three invasion beaches on Betio at the speed of four knots. By the time the first amtracs crawled over the exposed reef, every gun on the island was blasting away at the Marines.
Slow-moving amtracs proved easy targets for accurate Japanese gunfire. According to a survivor, the approach turned into a "nightmarish turtle race" with bullets "pouring at us like a sheet rain. The enemy fire was awful damn intense and getting worse. They were knockin' boats out left and right. A tractor'd get hit, stop, and burst into flames, with men jumping out like torches." Gilman's amtrac approached Betio at Red Beach 3, a section of sand near the long pier. He made it all the way to shore before lodging on the wooden seawall. "The amtrac just hung there, tipping back and forth. Someone yelled, ‘Everyone get out!'"
Few Marines joined Gilman's group in the early hours of fighting on Betio. Most of them clung tenuously to a narrow beachhead next to a seawall. Marine Col. David M. Shoup, commander of the first three waves, tried calling for reinforcements, but every radio was ruined by seawater. For 90 minutes, he operated without contacting his superiors.
Shoup got little help from succeeding waves of Marines, who had entered their own version of hell. Since water levels at the reef were low, successive waves without amtracs had to wade 700 yards, through withering fire, from the beach to the reef. It was an agonizingly slow trudge.
By 10:30 a.m., Shoup had located an operable radio and sent an urgent request for reinforcements: "We need help. Situation bad."
When darkness settled over the battered isle, 5,000 weary Marines huddled on Betio's beaches. Already, 1,500 of their comrades were either dead or wounded.
At night, they feared the Japanese would unleash a bloody counterattack against the thinly held American beachhead. Dawn broke, however, without a stir. Though it had failed to destroy enemy bunkers, the naval assault succeeded in accomplishing two objectives. First, the intense bombardment shattered communication wires Shibasaki had spread over the island. More important, a salvo from a U.S. destroyer had ripped into a group of Japanese soldiers as they fled from their bunker, killing them all. Among the slain was Shibasaki.
The second day brought new horrors. Water on the reef was still low, so Marines again had to walk the bloody gauntlet to shore. From his position at the seawall, Gilman watched those Marines in the water slowly advance, amid exploding shells and thousands of machine-gun bursts. He thanked God he was already ashore. "What they had to go through," he later recounted, "was unbelievable."
The Marines advanced a yard at a time. The Japanese had placed their pillboxes so that if one were charged, the other two opened fire. The strategy exacted a horrific price. "We jumped into the foxholes and emplacements, and bayoneted them or shot them," said Pfc. Robert Muhlbach. "There was a lot of bayoneting. I don't know how many I killed during the three days."
During the next afternoon, the Marines noticed small but measurable progress. Water over the reef rose around noon, allowing larger ships to ferry in sorely needed reinforcements, drinking water and supplies. Bolstered by more men, Marines advanced across the middle of Betio to divide enemy defenders. Other units started clearing up the southwest portion of the isle. For the first time since the battle started, victory was within reach.
Shoup reported to shipboard superior officers: "Casualties many; percentage dead not known; combat efficiency: we are winning."
The next day, Marines attacked the remaining Japanese strong points, using TNT, hand grenades and flamethrowers to demolish pillboxes, and called up bulldozers to smother the stubborn enemy in his own dirt. Japanese defenders, knowing the end was near, committed suicide. Some thrust bayonets into their stomachs in imitation of the ancient Japanese tradition of seppuku. Others held hand grenades to their heads, or placed rifles against their throats and pulled the triggers with their toes.
At 1:12 p.m. on Nov. 23, after 76 hours of some of the fiercest fighting in Marine Corps history, Betio was officially declared secure.
Marines incurred frightening casualties: 2,292 wounded and 1,027 killed. For many, death was so ghastly that only 565 bodies could be identified. Time correspondent Robert Sherrod called the shell-shocked isle "one of the greatest works of devastation wrought by man. Words are inadequate to describe what I saw on this island of less than a square mile. So are pictures - you can't smell pictures."
When news of Tarawa and the accompanying photographs reached the United States, the public reacted with revulsion. Many wondered if the assault had been worth the cost, but military leaders agreed Betio taught valuable lessons. Battle reports were studied carefully and led to changes in the way Americans would invade all future Japanese atolls. As one officer concluded, "There had to be a Tarawa, the first assault on a strongly defended coral atoll ... There, untried doctrine was tested in the crucible of actual combat."
Four men received the Medal of Honor for heroism at Betio, including Shoup, who later served as Commandant of the Marine Corps in the Eisenhower and Kennedy administrations.
Nearly every participant showed unfathomable courage. "Those men who won the Medal of Honor were brave, but everyone was brave," Gilman said. "Anyone who says he was not afraid on Betio is lying, but even with the fear, they did what they were trained to do. Each man who took another step forward, in the water or on land, was a hero."
John Wukovits  is a military historian and author of "One Square Mile of Hell: The Battle of Tarawa."