On the morning of November 20, 1943, the tide around Betio Island in the Tarawa Atoll refused to rise the way the charts said it would. “From here on you can walk in,” a boat officer told the fifteen men crouched behind him, and the ramp went down five hundred yards short of the sand. The reef had done what no amount of naval gunfire could do. It had stopped the boats cold, half a mile out, in three feet of water where the planners had promised five.
Time correspondent Robert Sherrod, riding in with the fourth wave, had spent the voyage over assuming the pre-landing bombardment would leave nothing alive to shoot back with. He was wrong within the first few hundred yards. The men climbed over the gunwales into the lagoon and started walking chest deep, rifles held overhead, toward an island a mile long and less than half a mile across that held a garrison numbering in the low thousands. Japanese soldiers and Korean laborers, both dug into bunkers the bombardment had left mostly untouched, opened up with machine guns from three directions at once.
Some men went under and did not come back up. Others floated face down, and at a distance, their own comrades took them for driftwood. A New Zealand army officer with fifteen years of lagoon experience on the atoll had warned before the landing that the tide would run low. Command overruled him.
The neap tide that morning just sat there barely moving, and it stayed that way through the worst of the fighting. Rear Admiral Keiji Shibazaki, the Japanese officer commanding Betio’s garrison, had told his men before the invasion fleet ever appeared on the horizon that it would take a million American troops a hundred years to take the island from him. Seventy-six hours after the first wave went in, American commanders counted close to a thousand Marines dead and better than two thousand wounded, cut down in a wade that never should have had to happen. Shibazaki did not live to see how wrong that boast turned out to be.
Most of the atolls the United States would fight across for the rest of the Pacific War shared the one feature that had done the real damage at Tarawa. A fringing coral reef sitting just offshore, invisible from a spotter plane at altitude and indifferent to what a landing plan assumed about how deep the water over it would be. Rear Admiral Richmond Kelly Turner had commanded the naval force that put those Marines ashore, and he did not wait for the after-action reports to draw his own conclusion. No amphibious operation under his command, he said afterward, would ever again go in without knowing exactly how deep the water was, or without some way to clear whatever the enemy had put beneath it before the landing craft arrived.
Solving that problem fell to a Naval Reserve lieutenant commander named Draper Kauffman. Kauffman was an odd choice on paper. Poor eyesight had cost him a regular commission out of Annapolis in 1933, so he went to work for a steamship line instead, then volunteered as an ambulance driver in France when the Germans invaded in 1940. He was captured, held for two months, and released, at which point he made his way to Britain and joined the Royal Navy, where he spent the Blitz diffusing unexploded German bombs and mines by hand.
By the time the US Navy called him home to build something new, he had already made a career out of the kind of work most men are trained to run away from. Kauffman set up a training school at Fort Pierce, Florida, in the summer of 1943, built around a working theory that a man could sustain something like ten times the physical output most men were assumed to have. The men who survived his final week, a seven-day stretch run on almost no sleep that later generations of Navy divers would call hell week, became naval combat demolition units. Six enlisted men and an officer to a crew, trained to blow beach obstacles under fire.
Most of them were slated for the coming invasion of France. Tarawa changed the assignment before most of them ever shipped out. Turner ordered thirty officers and 150 enlisted men staged at Waimanalo on Oahu to build a Pacific version of the same idea. Most of them came out of the naval construction battalions, the Seabees, men who had already spent the war building airstrips and piers under fire and knew their way around a case of dynamite before the Navy ever asked them to swim toward one.
These first underwater demolition teams did not yet have a settled method. What they had was a standing order to find out what was waiting in the water before the fleet showed up again, and permission to figure out how. They found the how at Kwajalein in January 1944. Two men, an ensign named Lewis Luehrs and a chief petty officer named Bill Acheson, were sent to check the reef ahead of the landing.
Regulation called for reconnaissance gear and a lifeline run back to the boat. Luehrs and Acheson stripped to their underwear instead and swam the reef alone in daylight, in plain sight of anyone on the beach who cared to look. They came back with sketches of Japanese gun positions, a log wall built to block landing craft, and the depth soundings the planners had asked for in the first place. Accounts differ on whether that swim was Turner’s intention from the start or the two men’s own improvisation once they were already in the water.
The record does not settle it either way. What is certain is that it worked, and that it reset what an underwater demolition team was for. The lifelines went away. The bulky gear went away.
What replaced it all was a man in swim trunks, a mask, and a pair of fins, which turned out to be cheaper, faster, and far harder for a shore battery to hit than anything wearing a rubber boat. Within weeks, Turner had a second training base running at Kahoʻolawe, built to teach the Kwajalein method rather than the Fort Pierce one. Most of the old procedure was thrown out. Lifelines were banned outright.
Swimming, not boat handling, became the center of the course. And the daylight approach in swim gear stopped being an improvisation and became the doctrine every new team learned from its first week in the water. By June 1944, off Saipan, that doctrine had grown into something close to an assembly line. Two hundred swimmers went in a full day ahead of the landing, painted blue from head to foot to blend with the lagoon, working in pairs a hundred yards apart.
Where the water ran shallow, they turned their own bodies into measuring sticks. A black line marked every twelve inches from ankle to collarbone, so a man could read his own depth off his own skin without ever surfacing to check a gauge. Where it ran deeper, they dropped a weighted line and wrote the number on a plexiglass slate strapped to one knee. Japanese gunners fired on all of it from the beach the entire time.
Kauffman himself, in the water at the front of his own team, earned a second Navy Cross there. Soldiers and sailors who watched them work from a distance took to calling the swimmers “half fish, half nuts,” which was not far off. What the swimmers also discovered, and passed down the buddy pairs faster than any manual could have written it, was that a rifle bullet loses most of its energy the instant it crosses from air into water and begins to sink within a few feet of the surface. A man who ducked his head at the right moment let the war pass a yard over him, which bought just enough time to finish a sketch, drop a line, and move on to the next hundred yards of reef.
The demolition itself was just as unglamorous as the reconnaissance. Explosive charges came packed into lengths of rubber hose that a swimmer could coil around a wooden piling or tie flat against the base of a concrete obstacle, one length wired to the next by primacord, so an entire row went up on a single simultaneous charge instead of one obstacle at a time. It was closer to plumbing than to combat, done by men lying flat in two feet of water with a knife, a roll of tape, and whatever length of fuse the job required, and every charge had to be set, wired, and the swimmers clear of the reef before anything went off. A month later, ahead of the landing at Tinian, Kauffman’s own reconnaissance changed the plan itself rather than just clearing a path through it.
Admiral Turner had intended to put the invasion force ashore opposite the well-fortified town of Tinian itself. Swimmers from underwater demolition teams five and seven, working with Marine reconnaissance troops, swam in at night to two narrow, unlikely strips of beach the local garrison had judged too small to bother defending, and came back with soil samples proving landing craft could use them after all. Kauffman crawled the sand himself to check the approach, broke his last remaining pair of spectacles rolling into cover when an enemy patrol passed close enough to hear, and reported back before dawn that the beaches would hold. Turner changed his plan.
The Fourth Marine Division landed there on July 24 against light resistance, instead of the fortified front door the defenders had spent months preparing to hold. That was the method Japanese defenders on beach after beach spent the rest of the war unable to counter, because by the time they understood what they were looking at, the men who had done it were already gone, and the only evidence left behind was a channel that had not been there the day before. At Guam that same month, underwater demolition teams three and four spent close to two weeks working the approaches to Agat under naval gunfire cover, charting channels and blasting the log cribs, coral heads, and wire entanglements the garrison had spent the better part of a year building into the shallows, obstacle by obstacle, on the assumption that whoever came for the island would have to cross them first. Ensign TD Nixon of Team 4 was killed by a sniper while guiding landing craft through the cleared channel the day before the assault, the only man his team lost in the whole operation.
On that same stretch of beach, some of Team 4’s men found the time to raise a hand-painted sign facing the water: “Welcome Marines. ” It was still standing when the first wave came ashore on July 21, proof before a single infantryman had set foot on Guam that the men who would greet him there had already come and gone, cleared the channel in front of him, and buried their own dead doing it. Three months after that, at Peleliu, the Japanese commander, Colonel Kunio Nakagawa, tried something no other garrison had managed. Reconnaissance swimmers from underwater demolition team 10 had gone in that August aboard the submarine Burrfish and mapped what was waiting in the shallows off the invasion beaches: concrete tetrahedrons, a double row of wooden posts about seventy-five yards out, barbed wire, and rows of horned contact mines, all of it sitting in water barely two feet deep at low tide.
Starting September 12, three days ahead of the landing, teams six and seven went in under direct fire to blow the posts and mines and cut channels through the reef, working two and three days running in water shallow enough that a man could be seen from the beach the whole time he worked. Nakagawa had stealth swimmers of his own, and the American activity itself gave him a rough idea where the landing would fall. He sent his men out the night before D-Day to lay fresh rows of horned mines 150 yards off the beach, a genuine attempt to rebuild in darkness what the Americans had spent three days tearing apart in daylight. He went further still, stationing swimmers in the shallows to serve in effect as human mines against the first tanks and armored amphibians that came ashore.
Neither countermeasure worked. His suicide swimmers were caught and killed before the landing began, and the relaid minefield failed for the smallest possible reason. In the rush, most of his men forgot to pull the safety pins. American landing vehicles rolled over mine after mine on September 15, and nothing happened.
Post-landing sweeps found the crushed contact horns still primed and still harmless. A live minefield that had never been armed at all. By April 1945, off Okinawa, the obstacle itself had gotten simpler and the job had gotten far bigger. The Japanese had driven pointed wooden poles into the coral to hold any landing craft that tried to cross.
Teams 11 and 16 went in to blast them clear along thirty miles of coastline. Team 16 took out about half its assigned poles before losing a swimmer and pulling back for the day, a mission the record books still call a failure. Team 11 finished every pole on its own stretch of reef, then stayed in the water afterward to guide the landing craft in by hand. Nearly a thousand men went into the water for that one operation, drawn from eight separate teams, working in currents cold enough, for the first time in the program’s history, to threaten them with hypothermia rather than heat stroke.
Some of those teams spent the same days staging fake reconnaissance runs off beaches the actual landing had no intention of using, just to keep Japanese intelligence guessing about where the real one would fall. None of these men carried a weapon beyond a sheath knife. Turner put in for decorations on a scale the Navy seldom handed out for a single campaign, silver stars and bronze stars by the dozen for the swimmers who had worked the Marianas that summer, an unusual overcorrection for a program that had not appeared in a single newspaper back home. The Navy did not even give them a proper service rating or an insignia to wear for most of the war.
A man in one of these teams was, on paper, still whatever he had been before he volunteered, a Seabee or a machinist’s mate who happened to also swim through minefields for a living. None of them were announced to the public until the war itself was over. And even then, the Navy’s own press releases credited much of the achievement to the Seabees, who had supplied something like half the swimmers, rather than to the program by name. What they had done, reef after reef, was swim into range of an enemy who was still loading his weapon, take the only kind of fire that could reach a man in open water, finish the job, and be gone before he understood what he had just watched happen.
That is what a Japanese defender found walking his section of beach at first light on invasion morning. Not an empty sea he could still hope to hold, but a channel someone else had already opened while he slept, marked, charted, and handed over to the men now climbing out of the boats behind it. By the time Japan surrendered, thirty-four underwater demolition teams had passed through a pipeline that started with two men and a pair of underwear off Kwajalein twenty months earlier. And every contested landing the United States made in the Pacific after January 1944, from the Marshalls to the black sand at Iwo Jima to the cold water off Okinawa, had a reef somebody had already been in before the first Marine ever got wet.
The men who did it went home afterward to jobs the Navy had never bothered to rename them for, and most of them are the only ones left now who remember exactly which beach they cleared, and on what morning, and what it looked like from the water when the boats came in behind them at last.
