Amphibious Warfare

by JAMES PHINNEY BAXTER

1

SHORTLY before Germany plunged Europe into war, a battalion of United States Marines, in amphibious maneuvers in the Chesapeake, climbed over the side of a battleship down cargo nets to 50-foot motor launches. In 1944—1945, task forces lifting three to six divisions put whole armies ashore in Normandy, Southern France, and the Pacific. In the space of five years, what Admiral King has called “ the most difficult of all operations in modern warfare” had been entirely transformed by an amazing series of developments in most of which scientists played an important role.

The concept of utilizing control of the sea to launch an overseas expedition of wide strategic possibilities is a very old one. The student of grand strategy will still find much food for thought in the British use of such expeditions in the Seven Years’ War and the Wars of the French Revolution and Empire. But the technological developments of the nineteenth and early twentieth centuries had strengthened the defense to such a degree that, by 1939, opposed landings on hostile shores seemed too hazardous for contemplation. The mine, the submarine torpedo, heavy ordnance, and land-based aircraft were generally assumed to have made the great land powers immune from overseas attack.

It was not sufficiently realized that one man’s poison may be another man’s meat: that the submarine, customarily regarded as par excellence a defensive weapon, could play an important role in an amphibious attack. Nor was it foreseen that an umbrella of aircraft could control the air, and help control the surface, as an amphibious force approached its target, and that the development of communications would permit it to team up with surface vessels in placing so heavy a fire on hostile shores as to make possible the establishment of a beachhead and the interdiction, or at the least the curtailment, of counterattacks by enemy air and ground forces during the initial period of the build-up.

In the pre-war discussions at the Army or Navy War College or in the War Plans Divisions of the two services, an officer would have been regarded as an impractical dreamer if he had suggested that the classic theories of step-by-step advance across the Pacific should be scrapped, and that an American task force, of a size and kind hitherto undreamed of, could by-pass important enemy bases in the Carolines, including Truk, then believed to be a sort of Japanese Gibraltar, and seize bases in the Marianas and Ryukyus from which long-range bombers could burn and blast the cities of Japan.

The armchair strategist who talks glibly about bold advances usually fights shy of what Mr. Churchill is said to have referred to as “that horrid American word ‘logistics.’” If he neglects the all-important factor of supply, he will be committing as grave an error as the inventor who talks about perpetual motion with no concern for friction. The historians of World War II who write a century from now, with a long view of the development of naval strategy, will probably be less impressed with the great developments of communications and firepower than with our ability to maintain huge naval forces for months in active operations so far from our shores.

In World War I the main fleets were tethered to home bases by a line not over 450 or 500 sea miles long. In the Pacific in 1944—1945 such a distance might seem to a supply officer just a good long spit. It is easier to understand radar or the atomic bomb than to grasp how we were able to maintain our huge fleet for months off the shores of Okinawa.

2

BECAUSE of the comprehensive nature of amphibious warfare, the larger part of the new developments sponsored by the Office of Scientific Research and Development influenced its transformations. Some new weapons and equipment played much the same role in the landings in Sicily or France as they did at Saipan or Lingayen. Some had more importance in the European or Pacific theater than they did anywhere else. The amphibious operations in the Mediterranean and in Europe involved essentially short oversea movements, employing an endless amphibian chain belt to move and supply armies carried from the United StHtes and Great Britain to Africa, Sicily, Italy, and France. In the Central Pacific, possibly the “most amphibious” theater, the great distances and the fewer bases available resulted in longer lines of supply.

Amphibious operations in the South and Southwest Pacific theaters combined the features of those in the Central Pacific, the Atlantic, and the Mediterranean, and had special features of their own: a large land mass, less initial opposition but little land maneuver because of the jungle. Our potential in amphibious and land-based air power in these theaters permitted brilliant “end-run” landings and enabled us to achieve much with little in the way of troops, landing craft, bombardment, and striking forces.

Navigation from ship to shore was a minor problem in the great landings of the Central Pacific, which were “power plays” carried out in broad daylight. Here there was little or no concern about surprise, but it was an important factor in some pre-dawn landings in the South and Southwest Pacific and in the landings in Africa, Sicily, Italy, and France. On the way to his objective the officer commanding an amphibious force had Loran in his command ship as a navigation aid. The VHF (very high frequencies) tended to get tied up with tactical traffic but the National Defense Research Committee had provided an excellent alternative for night signaling in convoy.

In these night landings it was not easy to hit the right beach at the right time. To do this required accurate navigation, first from the transport area to the line of departure, where the attack was launched, thence to the hostile shore. To grapple with this problem the Chairman of NDRC, at Admiral Furor’s request, set up in April, 1942, a committee (later called Naloc) to study navigational aids to landing operations. The committee’s problem was to devise means of finding a beach within 200 yards of a target point and within one minute of H Hour from a position 5 to 10 miles off the coast, in the dark of the night and without compromising the security of the whole operation.

With the cooperation of the Navy, Naloc began testing radar and landing craft at Norfolk. Their program called for navigational tools and doctrine, for training, and for redesigning and procuring LCC’s (Landing Craft Control) to lead other craft to the beaches.

During the summer, tests went ahead at Fishers Island and at Woods Hole on radar and radio sonobuoys, fathometers, odographs, and gyrocompasses. The SG radar could furnish tangents and ranges, but the NDRC scientists came up with another device, the Virtual PPI Reflectoscope, something like a Disney animated chart, which enabled a navigator to determine the position of his ship by superimposing on his Plan Position Indicator the image of an actual chart. A refinement known as the Navigational Microfilm Projector replaced the paper chart by a system of lenses to project the image of a small film on a screen. These devices were tested successfully on cruises along the Maine coast and in the Caribbean.

By October, 1943, LCC’s designed to carry this gear were coming from the production line at the rate of one a week and trained crews were ready to man them. The craft had excellent compasses, fathometers, and communications equipment, but were too uncomfortable for the necessary prolonged use by their crew. They proved too large for ready handling overside from an assault transport and too small to go any distance under their own power in heavy weather. They were generally replaced as primary control craft by the PC’s (submarine chasers), but they did good service in numerous operations as secondary and tertiary control craft.

As secondary control craft on D Day in Normandy, for example, they accompanied the PC’s to a line 3000 to 4000 yards off the beach, where tank landing craft unloaded their amphibious tanks. Then the LCC’s led the tanks to within 400 yards of the shore, returning to the line of departure to help control smaller craft. On D Day they assembled and dispatched 25 assault waves from the transport area. As tertiary control craft they put over the buoys for the Mulberry and Gooseberry docks.

In anticipation of amphibious attacks, the Germans and Japanese expended considerable effort and ingenuity on underwater defenses. A steel rail with one end sharpened to a point and the other imbedded in a large block of concrete was a likely device to skewer a landing craft and a difficult item to blow up or move away. Mines were interspersed among the various obstacles in such profusion that an invader who timed his arrival for low tide would have a hard time clearing a lane on the beach before the tide rose enough to complicate his operations. The Japanese made effective use of coconut logs in bolstering the already formidable protective screen of natural coral reef at Tarawa before our attack in November, 1943.

Two months earlier a Joint Army and Navy Board on the Demolition of Underwater Obstacles had been established at Fort Pierce, Florida, and at Navy request, NDRC had set up a committee, later known as the Doloc, to collaborate in the work. It was clear that demolition of underwater obstacles by hand-placed charges would be costly under enemy fire, and that mechanical aids were much to be desired before the Normandy and Pacific landings of 1944. The deadline set for the gear to be on the dock for shipment, February 1, left too little time for satisfactory solutions and showed up the limitations of forced-draft research. Such research may work in developing a specific piece of apparatus, but even good men will often fail to solve a highly complex problem against an early deadline.

Within the time limits set it was clear to the members of Doloc that they could not develop satisfactory new weapons. The best they could do was to take existing weapons, make hasty improvements, demonstrate their possibilities, and make suggestions for their tactical use. It was also clear that no single device would be able to demolish the variety of obstacles likely to be met: deep-water mines, shallow-water mines, water obstacles, wire, dragon teeth, traps, and beach walls. The brilliant successes of the Navy underwater demolition teams and the comparable Engineer units were duo to their training, their courage, and their leadership, rather than to anything the scientists could do to help them.

3

THE two chief problems of amphibious assaults were the control of traffic from the transport area to and from the beaches and the massing of firepower to cover the landings. Both were the subject of constant study, resulting in a long evolution of tactical doctrine as our new weapons and equipment came into use and the enemy introduced weapons of his own and methods of countering ours. Both problems laid tremendous burdens on communications and led to the introduction of special command ships with every variety of communications channels and a wealth of radar and sonar information. A parallel development was the installation of Combat Information Centers in destroyers and headquarters ships for the tactical control of aircraft over the targets in the Pacific theaters.

The use of deception in amphibious operations varied greatly with the theaters. In the great landings in Normandy and in Southern France it was carried to the peak of perfection. On D Day the Germans were convinced that the operations in the Bay of the Seine were a feint, or at best a secondary operation, and that the main attack was coming in the Pas-de-Calais.

Tactical surprise saved thousands of lives, at the very least, if not the success of the whole operation. Here the radar countermeasures experts gave full rein to their imagination and turned loose a bewildering array of jammers and deception devices. They blinded the eyes of enemy radars to conceal the true direction of the Allied attack and filled the German scopes in the Pas-de-Calais area repeatedly with the fanciest imaginable assortment of simulated echoes. A ghostly procession of nonexistent battleships, cruisers, destroyers, transports, landing craft, and air squadrons swam into the German’s ken, thanks to the most sophisticated faking in the history of man.

This was what one might call a single-wing offensive in the field of deception. We faked a play straight through the center of the line and smashed off right tackle. To ensure the success of the landings in Southern France on August 15, 1944, we resorted to a double-wing offensive. We created the illusion of sweeps around both ends and smashed straight ashore through the center. The illusion we created was so perfect that the Germans expected a landing in the Bay of Genoa to the east and another far to the west of our actual landings.

Hot debate has raged as to the use of smoke as a screen for an amphibious landing. There has been no dispute as to its indispensability in screening the transport area whenever necessary between dusk and daylight against enemy air attack. For that purpose it was as necessary as radar or sonar. Between the landings on Leyte, when the Japanese first countered with kamikazes, and those on Okinawa, there was a tremendous growth in the use and application of the smoke tactics developed for the Marianas operations. Smoke became a major concern in logistics. One shudders to think what would have happened to our fleet off Leyte, Lingayen, or Okinawa if smoke had not been available to shroud it.

When an airplane approaches a transport area veiled in smoke the bombardier has little time in which to make his decisions. He must do so long before he is directly over the target and must consequently look through a thickness of screen considerably greater than its perpendicular depth from top to bottom. Because of this, and the fact that he has flak and his instruments on his mind, a smoke screen may be much more effective against him than it would be against an unhurried observer.

If smoke was used in daylight hours it often blinded our own anti-aircraft gunners, and if whipped along the surface of the water in a strong breeze it sometimes broke into eddying patches which only partly concealed our ships.

The offensive use of smoke to cover the assault waves was another story. In theory, if the wind was onshore, you could send a cloud of smoke ahead of the first wave to blind the eyes of the enemy. But what if the wind changed and the smoke rolled back over your coughing, choking men, throwing the landing craft into confusion? Theoretically, smoke could be used on the leeward flank of a landing force to screen it against enfilading fire. Here again there was a risk of a change of wind. Where everything depended on accurate timing and the perfect control of the ship-to-shore movement, was it wise to take chances? Admiral Turner did not think so.

His classic landings in the Central Pacific were “power plays,” with little or no need for deception. The airfields from which enemy air attack might come had been carefully neutralized by sweeps of carrier groups and bombardment by cruiser divisions. A striking force of fast battleships and carriers was at hand to dispose of the enemy fleet if the Japanese cared to risk it, as they did at the time of the landings on Saipan and Leyte. And firepower so heavy that the figures fail to give any adequate idea of it was massed on the enemy targets — firepower better controlled than ever before, and applied after careful study of the effects of previous land bombardment.

“How are you feeling?” asked Vice-Admiral Harry Hill of a wounded Marine who had just been brought back to his ship off Saipan. “Fine, thank you, sir,”replied the wounded man. “I was in the thirteenth wave today. Next time I hope to be in the first or second.” There spoke an old hand who knew the paralyzing effect on the defenders of a preliminary (pre-assault) barrage laid down by surface vessels when combined with bombing and with artillery fire from land bases.

In the attack on Munda in 1943, pains had been taken to secure advanced bases from which fieldpieces could be brought to bear on the main enemy positions. In defending an atoll as extensive as Kwajalein in 1944 the Japanese did not have men and guns enough to defend all the low islands surrounding the great lagoon. By means of A-frames the superb Dukws landed on an unoccupied island four batteries of 105-millimeter guns, which poured 75,000 rounds on the defenses of Kwajalein Island.

Here we were profiting from the lessons of Tarawa, as well as the experience of Munda.

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WHEN to end the barrage is one of the most critical decisions in an amphibious operation. If it is lifted too late it will mow down the men of our own first wave. If it lifts too soon, the enemy — or the part of the enemy that has not been killed, stunned, or badly wounded by the bombing and shelling — will leap to any guns still capable of action and sweep the beach with them. Was there any means of keeping the enemy fire down in the critical period between the time when the barrage had lifted and the first waves hit the beach?

Because of its recoilless feature and light construction, which permitted the installation of launchers on landing craft and gave them firepower equal to that of much larger vessels, the barrage rocket proved to be the answer. NDRC distinguished itself in the development of rockets and rocket launchers. Its expenditures for research on these weapons stood second only to those for radar. The successes of Division 3 did much to shape the development of amphibious warfare. Rockets fired from support boats — LCS(S) — helped to cover our landings in Sicily in July, 1943. United States forces took their first islands in the Pacific without them, but at Arawe, in December, 1943, two Dukws and two submarine chasers, each equipped with rocket launchers, helped to break down the beach defenses prior to the assault landings.

Their fire offered such a good solution to the problem of keeping the Japanese down, when the barrage lifted and the troops hit the beach, that the use of rockets spread rapidly in the South and Southwest Pacific theaters. The LCI’s (Landing Craft Infantry) could fire to cover a broad front, not merely straight ahead. LCT(R)’s (Landing Craft Tanks — Rocket), LCVP’s (Landing Craft Vehicles Personnel), and LCM’s (Landing Craft Medium) also carried rockets. An officer of the 2nd Engineer Special Brigade stated that as an instrument of morale they were extremely valuable: —

“It is much easier for troops to make an initial landing on a beachhead which they know has been well covered by rocket fire in advance of their landing. Second, as an antipersonnel weapon, the rocket is by far our most important weapon used in amphibious assault operations.”

The landings in Normandy were a halfway point in the development of rocket tactics. At Omaha Beach rocket craft took a position in close formation in line abreast, about 2700 yards astern of the leading wave of landing craft. They were to proceed in and deliver rocket fire when the landing wave was about 300 yards offshore. Their commanders, after the operation, pronounced rocket craft the most valuable of close-fire support weapons.

Leyte and Lingayen were big rocket shows, but Admiral Turner did not make much use of beach barrage rockets until the Okinawa landings. This may have been due in part to the enormous firepower at his disposal. He used the airborne rocket extensively, both as a pre-H-Hour weapon and in direct support of troops. Here the role of the rocket was a big one.

It was at Okinawa that rocket tactics reached their culmination. There the “Interim" LSM(R)’s (Landing Ship Medium — Rockets) fulfilled a variety of needs. They bombarded the beaches just before H Hour, harassed isolated strong points, patrolled against enemy suicide boats, and upon call supplied fire support to advancing troops. A single LSM(II) could hit a beach with 100 rockets a minute. With 15 craft loosing a barrage against a single beach — 7500 rockets in five minutes — a beach must have been almost as hot as an exploding ammunition ship. In another instance a rocket bombardment, before a landing, completely disrupted about 200 yards of a highway and of a small railway between Naha and the southern beaches, and thus effectively denied the enemy his use of reinforcements.

In affording call fire support at Okinawa LSM(R)’s came definitely into their own. Four LSM(R)’s, two on the east side of the island and two on the west, fired an average of two deckloads of rockets each, daily for ten days, in support of our troops pushing south. Rockets which arched over protecting ridges just inland from the landing beaches inflicted heavy casualties on retreating Japanese forces. In this action our commanders used air spot of rocket fire for the first time. Successful as its introduction was, it would doubtless have been even more valuable with “Ultimate” LSM(R)’s equipped with improved launchers.

In all uses to which the Interim LSM(R) was put, performance was impaired by the limited range of rockets, — 4000 to 5000 yards, — the time required for reloading, and inaccurate fire. Nevertheless it performed yeoman service. The varied ways in which rockets and rocket ships were now employed showed how the conception of their tactical uses had grown since their initial employment.

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OF ALL the devices specially designed by NDRC for amphibious warfare the Dukw was the most successful. Its versatility made it of use in all the amphibious theaters. When the staff planners were racking their brains as to how to land supplies on the coast of Sicily despite the shallow beach gradient, this seagoing 2½-ton Army truck came as an answer to prayer. The driver, able to adjust tire pressure without leaving his seat, could change the pressure to what would give him traction in soft sand, and the trick would be turned.

At first thought, it seemed preposterous to use rubber tires on jagged coral which tore the steel tracks off other amphibians. But exhaustive tests on the Florida Keys showed that rubber tires with the right pressure — 30 pounds — could take the beating and still hold up. As a result of these tests Division 12 of NDRC evolved the doctrine of a particular tire pressure for a particular terrain — 10 pounds pressure for soft sand, 30 pounds for coral, and 40 pounds for hard roads. This was only part of the job. The Army and Navy had to be convinced, too.

The Dukw was conceived primarily as a means of expediting discharge of cargo from ships, through surf if need be, to shore dumps. It made good in this role, though, as events developed, there were a number of other things it could do even better than serve as a general cargo handler.

The first Transportation Corps Amphibian Truck Company to be activated, the 451st, reached New Caledonia in March, 1943, the same month in which the Dukws first arrived in North Africa. But it was in Sicily that they scored their first great combat success. General Patton had been much impressed by a demonstration of these amphibians at Arzeu in April and had immediately requested increased numbers of them for the forthcoming invasion.

In the Sicilian landings of July 10, 1943, the British had about 300 Dukws, divided between two companies and a temporary group (which left England after only four days of Dukw training and came directly into Sicily). The Americans used about 700 Dukws.

The British Dukws landed without difficulty, and surf conditions in the British sector remained mild. But the American landings took place in heavy weather. Several transports smashed up boats trying to get them over the side. On one transport a 20-ton LCM swung back and forth over the deck like a charm on a watch chain. Two thirds of the LCVP’s and LCM’s broached in the surf, but the Dukws kept rolling. General Eisenhower declared the new amphibian to be invaluable. “It greatly facilitates flow of supplies over beaches and on one beach was used as assault craft. Mechanism should be kept secret as long as possible. We should be delighted to get some more of them.”

In the Ellice Islands operations in 1943, preloaded Dukws swam out of the LST’s to the amazement of those who saw them for the first time. To see ships well offshore opening their bows, letting down ramps, and disgorging Dukws was an incongruous picture. It resembled nothing so much as a novel and grotesque manifestation of the age-old business of birth. In fact, it was just that — birth of a tactic which became Standard Operating Procedure.

The Dukw was not used at Tarawa, but by. the time of the landings at Kwajalein Atoll on January 31, 1944, it was on the first team. It had found a new role, which some regard as the most important it played in the Pacific. This was to carry a preloaded artillery piece and initial ammunition ashore, unload by means of an A-frame mounted on a fellow Dukw, return to the parent LST, and shuttle ammunition and supplies till all were ashore. A well-trained crew could rig the A-frame, unload the piece, and hitch it to the Dukw pintle hook in seventy-five seconds. A battery could be set up in firing position within seven minutes of landing.

The Dukw had many advantages, which steadily increased its circle of friends. It could be carried on transports, usually on deck in place of LCVP’s or in small areas in between the LCVP skids. In action the Dukws’ wonderful bilge pump kept many of them afloat even when they had been severely holed.

As with all new equipment, mistakes in use of the Dukw were inevitable. Ranking officers of both Army and Navy were often ignorant of the capabilities and limitations of the Dukw. Because of their slow speed afloat — about 5 knots — it was inefficient, unless unavoidable, to have Dukws make a water-carry of much over a mile from ship to shore. Ships to be unloaded sometimes moored too far offshore. Dumps were sometimes too far inland. Because of their high speed ashore, there was constant temptation to take Dukws from their primary assignment for purposes of land transportation.

At times Dukws were overloaded or badly loaded. There was consequently a high loss both in vehicles and in tonnage hauled. Crews were sometimes green. Teamwork with crews of ships, on the one hand, and with crews at dumps, on the other, was sometimes ragged. Technical officers and men were often hopelessly inadequate in number to provide satisfactory maintenance. There seemed never to be enough spare parts.

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THE most crucial amphibious operation in history was Operation Overlord, the landing in Normandy; and circumstances conspired to make the Dukw virtually indispensable to the success of the operation.

The first companies landed on D Day —with the 1st Engineer Special Brigade on Utah Beach, and with the 5th and 6th Brigades on Omaha Beach. Loaded with high-priority engineering equipment, artillery pieces, and ammunition, these Dukws pushed through passages only partly cleared of underwater obstacles and mines. On the beaches they encountered heavy enemy fire as well as land mines. In contrast to the driver of a land truck, a driver of a Dukw rarely became a casualty if his vehicle detonated a mine. The front wheels and engine compartment well in front of the driver absorbed the shock of the explosion. Still, casualties did occur.

On D plus 3 the first of the Negro Dukw companies arrived on the beach in LST’s and LCT’s. To make land runs by Dukws as short as possible, transfer points were set up in the dunes close to the beaches. Though the beaches were of firm sand, the Dukws encountered other operating difficulties. The small North Sea coasters were used for cargo vessels because they are a difficult target and are able to operate close to shore. But they rolled violently in the rough Channel waters, and they had heavy side guardrails which caused much damage to Dukw hulls and headlights.

Sea conditions were bad much of the time, particularly at Omaha, which was partly open to prevailing northwest winds. Surf was high, and tides ran as fast as 3 knots. The shore was cluttered with wreckage and spilled cargo. There was consequently a high mortality to Dukw propellers and rudders. Maintenance became a nightmare but the Dukw met the test.

The first three weeks of the assault on France dem onstrated beyond question the usefulness and depend ability of the Dukw in the hands of an experienced operator. Not only did it move cargo from ship to shore, as other ferry craft could, but it could and did transport that cargo overland to a dump. This ability, possessed by the Dukw alone of all the ferry craft used in Operation Neptune, went far to solve the problem posed by a shortage of trucks and cranes during the first days on Omaha Beach. Again, following the storm of 19—22 June, it was the Dukw that enabled immediate resumption of the movement of large quantities of cargo. While the hulls of other types of ferry craft were being battered on the beach, the Dukws were safely ashore in their parks, waiting to begin work when the storm abated. Undoubtedly, the present model of the Dukw is susceptible of modification and improvement to give it greater sturdiness, but, with all its imperfections, it converted this beach operation from what might have been a random piling of supplies on the beach to an orderly movement from ship to dump.1

The Germans had been sure that even if the Allies succeeded in landing, they could not bring enough supplies across the open beaches of Normandy to support a major offensive. The Wehrmacht had only to gather strength and drive the Allies back into the sea. When the great storm destroyed the improvised breakwater, the very survival of the Allied field armies depended more than ever on the Dukw.

In spite of all difficulties, the Normandy beaches continued to serve as major ports into the late fall, with Dukws bringing ashore 40 per cent of all supplies landed between June 6 and September 1. They sustained Generl Eisenhower’s reporl on their high value in the Sicilian landings. Altogether, approximately 2000 Dukws were operating on the coast of Normandy by D plus 60. Even so, Operation Overlord hardly represents the culmination of Dukw tactics in themselves.

Report of the Engineer Special Brigade Group.

In the Pacific the going was often heartbreaking. At Iwo Jima, for instance, beaches were so steep that the front wheels would bury in the soft volcanic ash before the rear wheels could obtain proper traction. Hit by heavy surf, a vehicle would be swung broadside and swamped, if not towed out without delay by tractors. A few spots were found where, with tires deflated as low as 5 pounds, the Dukws could climbout themselves. They were under mortar and small-arms fire much of the time and their hulls were often punctured in many places. Shore conditions were so critical for a time that Dukws had to put back to sea regardless of seaworthiness, and several LST’s were designated as repair ships.

Though losses in Dukws during the first five days of the Iwo operation were 50 per cent, casualties among Dukw drivers were light—each company of approximately 184 men averaged about 3 killed or missing and 10 wounded. General Holland M. Smith, Commanding General of the Fleet Marine Force, commended the Army Negro drivers for their courage and skill. Their performance led the Marines to request training for their Dukw companies in the Dukw school at Oahu under supervision of OSRD personnel.

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AT Iwo Jima, Dukws took on another major role for which their ability to swim in and out of an LST ideally qualified them. This was transporting casualties directly from field stations to hospital ships. Otherwise it was necessary to carry casualties back to the beach by truck, then by litter through surf to landing craft. Gravely wounded men could hardly stand so much handling. But by carrying thousands of casualties untouched from field stations to hospital LST’s, Dukws unquestionably saved many lives.

In the Central Pacific landings, LVT’s (amphtracks) were used more extensively than Dukws for cargo transfer because there were more LVT’s, and the Dukws available were in high demand for specialized tasks. But their role in transferring cargo was highly important, as at Saipan, Guam, Peleliu, and Angaur, especially in the early stages of a landing, when channels for LCVP’s, LCM’s, LCT’s, and LST’s had not yet been blasted through the reef.

As one control officer described the operation: —

We would load LCVP’s, LCM’s. LCT’s, and pontoon barges with high-priority cargo (and in the early stages with reserve troops) and send them in to a “transfer area" off the reef. Empty LVT’s, and Dukws would come off the beach, cross the reef, transfer cargo from the boats (under the direction of primary and secondary control officers in PC’s and LCC’s at the Transfer area) and take the cargo back across the reef to the beach dumps. Refinements included: (1) landing LCT’s and LST’s on the reef, where LVT’s and Dukws could drive into them for loading; (2) anchoring pontoon barges off the reef to make it easier for LVT’s and Dukws to come alongside for loading; (3) loading the pontoon barges with gasoline drums to provide offshore filling stations for LVT’s and Dukws, when the opposition was too tough or the beach too rugged to land the drums and establish fuel dumps ashore.

American resourcefulness turned the Dukw to many uses. Dukws were landing artillery pieces during early phases of an assault — as in the surprising “end runs” up the Italian coast at night to turn Kesselring’s flank. They were mounting rockets and artillery. They were evacuating wounded from shore to hospital ship. They were laying communications wire across water channels. They were landing troops over reefs and sand bars which hampered the usual craft for carrying personnel. Ashore they were towing vehicles and transporting both men and supplies. They were useful in underwater salvage work. And on occasion — as at Saipan, where a freighter was hung on a coral reef with solid seas breaking over her and washing men off her decks — Dukws rescued shipwrecked crews. By the end of the war, over 21,000 Dukws had been procured besides nearly 7000 more whose production had been authorized. Enough companies had been trained to man 5000 to 6000 vehicles.

Years from now, under different conditions as to secrecy, when the archives of all the combatants are equally accessible, an historian of amphibious warfare may be able to trace in minute detail the evolution of the Standard Operating Procedures of friend and foe, and show with precision the influence of each new weapon and each countermeasure in the evolution of tactics. Even now the main lines are clear. Because naval power, air power, and land power merge in amphibious operations, the greater part of the contributions made by the scientists who came to the aid of the Army, the Navy, and the Air Forces helped to increase our amphibious might.

It is well that they did, for in no earlier war had leaders even dreamed of amphibious attacks on such a scale. Nothing but the immense stakes and the lack of a satisfactory alternative would have justified taking the risks involved in the Normandy invasion. The great contributions of the scientists lent confidence to the chiefs who shouldered this terrible responsibility, to the planners who conceived the complicated procedures, and to the brave men who carried them out. The new weapons and equipment saved thousands of Allied lives in forcing open the European and Pacific fortresses. Indeed, without them it is hard to believe that the invasions could even have been attempted.