The Amphibian Tractor, Jack of All Missions

"This operation would have been impossible without the Amphibian Tractors." Here is a statement which has appeared with unerring consistency following nearly every amphibious operation in the Pacific theater of operations. This is the case because the "amphtracs," as they are popularly called, are the only truly amphibious craft capable of proceeding at sea, crawling over nefarious coral reefs, traversing the soft sand beaches, and maintaining an offensive barrage of machine gun or heavier ordnance fire all simultaneously.

This Landing Vehicle Tracked, as it is officially marked, is singular in its ability to debark the infantry, or high priority cargo not necessarily on the water's edge, or littoral portion of the beach proper but anywhere that the tactical situation demands, roads, bridges, streams, and swamps notwithstanding.

This rather odd craft, propelled both afloat and ashore by a tank track fitted with small paddles or grousers, has eliminated the laborious and usually dangerous work of unloading cargo at the water's edge as is the ease with landing boats. It has obviated the equipment of piers, transfer of cargo to trucks, availability of roads and bridges; and has ignored the obstacles of slope and swamp. These abilities and characteristics, so necessary in the operations in the tropical islands of the Pacific, have rendered this vehicle a sine qua non of amphibious warfare,

The "Love Victor Tare," like most naval craft employed in amphibious warfare of World War II, was born of necessity. Oddly enough, however, this unique craft was born of the mother of Mercy rather than the father Mars. In the middle thirties after several fatally disastrous hurricanes in southern Florida it was recognized that many lives could have been saved from the impenetrable reaches of the Everglades region if there were in existence some machine capable of negotiating these flooded swamplands which had isolated and claimed the lives of so many hapless victims, separated from all hope of supply of food or medical assistance. Into this breach stepped Mr. Donald Roebling of Clearwater, Florida, who with his technical and mechanical genius began experiments in his own shops on just such an amphibious vehicle as the urgencies of humanity required.

The original experimental models were constructed of all aluminum in order to keep weight to a minimum and hence reduce the pounds per square inch ground pressure to  a figure which would not only enable the craft to "float" over the vast swamplands but also give it a reasonable speed of some 10 knots in water.

Two of these first models were turned over to the Naval Air Stations at Opa Locka (Miami), Florida, and Corpus Christi, Texas, the third was retained by Mr. Roebling for local rescue use. The first two have served with an astounding record of rescues of not only hundreds of pilots downed in the otherwise unapproachable badlands of these naval air training areas, but of the very planes themselves. To conquer these morasses the amphibian tractors of that date (circa 1941), were equipped with first-aid devices, two-way radio, salvage mechanisms, and every variety of personnel and material saving device possible to install. They were kept in a ready condition at all times mounted on fast trailer beds drawn by powerful prime movers. At the call of distress this auxiliary unit would haul the "Alligator" as far as possible in its approach to the downed pilot and plane, debark it and permit it to proceed on its merciful and amphibious mission.

In 1940 the U. S. Marine Corps recognized the possible value of such a craft as ideally suitable to the generic naval-military concepts of that organization. Upon approaching Mr. Roebling with the prospect of employing this invention as a machine of war, the Marine Corps met with objections to the effect that the machine had been devised to save, not destroy lives. In the spirit of true patriotism, however, the Alligator was enlisted in the service of its country and turned over to the cognizance of the Bureau of Ships for such development and use as was seen fit.

The first tests of the Alligator were effected by the Fleet Marine Force on winter maneuvers in 1940, on the island of Culebra, Puerto Rico, and later at Virginia Beach, Virginia. The results were so gratifying that the Marine Corps immediately began study of certain design and engineering changes which would adapt the craft to military use. A contract was let to the Food Machinery Corporation at Dunedin, Florida, very near to Mr. Roebling's Clearwater establishment, for the manufacture of the first few amphibian tractors

Without the men to operate them the Alligators would be just so much steel and fiber, so the U. S. Marine Corps, in May of 1941, established the Amphibian Tractor Detachment at Dunedin, Florida, for the technical and operational training of the men who were soon to compose the nucleus of the many amphibian tractor battalions, and soon to ride roughshod over the coral reefs of the Pacific to the utter amazement of the boat-minded Japanese. Trainees arrived from the Army, Navy, Marine Corps, and even the Royal Netherlands Marines. So great was the press of training that another such establishment was initiated at the Boat Basin of Camp Pendleton, California, under the aegis of the Marine Corps and Navy.

From this time on the growth of the LVT's was a phenomenon quantitatively, qualitatively, and tactically. Contracts were let on huge scales to the Food Machinery Corporation which soon found themselves so Overtaxed that it was necessary to employ three of their entire plants for this production, at such scattered locales as Lakeland, Florida, Riverside and San Jose, California.

Demands for output were so great that it soon became necessary to contract to such concerns as St. Louis Car and Foundry, Graham Paige, and the Borg Warner Division of General Motors. These in turn further subcontracted to small producers for prefabricated parts or assemblies to a point where the basic producers were operating assembly lines. In 1944 LVT's had been turned out to a total well up in the five digit bracket.

The development of these craft was very interesting in that any person involved started nearly from scratch. There were no official "experts," little research data, and practically no "know how." Problems of water cavitation and resistance, r.p.m. vs. speed on land and water, and the usual mass of technical data necessary for effective construction were items to be evolved and developed to the peak of efficient combinations by a constant compromise with weight, dimensions, and ground pressure limits imposed by tactical and combat shipping requirements. No less important establishments than the Caderock Model Basin and the California University of Technology enlisted their best brains in the solution of this design problem. Research, development, and test units were established at the Engineering Experimental Station at Annapolis, the Amphibian Tractor Detachment Dunedin, Florida, and the Joint Army, Navy Experimental Test unit at the Amphibious Mental and Testing Board Training Base, Fort Pierce, Florida, while specially established testing grounds were set up at Camp Pendleton, California, by the Marine Corps. Various discoveries, inventions, improvements, and ideas began pouring in at a rate as astounding as the characteristics of the data. A captured Japanese tank with jettisonable pontoons produced some ideas; a "mud buggy" invented for a large oil company in prospecting for oil deposits in the swamps of Louisiana added more information, while various "hams" and trained scientists contributed the rest, all working at a fever heat to turn out a service-designed combat craft to replace the reliable but vulnerable Alligator.

The basic concept of the Marine Corps for the use of these vehicles was a carrier for "hot cargo" over reefs and navigational hazards, in order to render an immediate initial resupply to the first assault waves prior to the time that piers or floating pontoon causeways could be established for handling small boat cargo. After the first such tactical use of the LVT's at Guadalcanal it was perceived that the employment of these craft as carriers of the assault troops against coral-fringed islands was not only the sole efficacious means of such transportation available but also a ruse which made it mandatory for the enemy to defend every foot of beach front of his defensive territory, since it could not be accurately estimated that an attack would necessarily approach through the normal boat channels. The effect of this was the spreading of these defenses to a dangerously thin depth. After depositing these assault waves of infantry at such locations on the target as directed, the LVT's normal mission included a series of return round trips with more supporting troops which were usually transferred from small boats at the "transfer line," well in toward the shore from the transport area. This device saved unnecessarily long water runs for the relatively slow amphibian tractors while water borne (about 5 to 6 knots).

After the establishment of front lines of attack inland the amph-tracs reverted to their originally conceived role of transporting the "hot cargo" to the troops that they had landed. When subsequently, the larger amphibious craft such as LST's, etc., were  able to beach, the LVT's then took up the mission of hauling cargo directly to the front lines to which roads and bridges had normally been rendered useless to wheeled traffic, or did not exist at all.

Since the LVT was a "craft," and would hence float, it was, per se, a naval responsibility and was hence put under the cognizance of the Bureau of Ships for control of production, development, tests, and distribution to the various using arms of both this country and various other of the United Nations. The first production models went to the Marine Corps, the pioneers of the craft, for use at Guadalcanal. Distribution to this arm was given priority for some time till the U. S. Army recognized the fact that since they would have to train amphibious assault units tantamount to the Marine Corps for landings, such a craft would be necessary both in the European and Pacific Theaters of Operations. The U. S. Navy used many of the LVT's as did the Army Air Corps, for air rescue missions, as aforementioned.

The above tabulated form is a progressive picture of the characteristics of the various models of the amphibian tractor. It might be here noted that the figures given are averages, subject to the variations due to development changes in the production line and altered tactical doctrine.

It is of interest to note that the LVT's were usually transported to the target areas in some ramp type amphibious attack vessel. LST's and LSM's were the usually employed varieties, however, the amph-tracs often found themselves riding in an LSV, LCT, or an LSD. On rare occasions the amphibian tractors were lifted by slings through their lifting eyes and placed in a cargo hold or on deck of a large cargo type craft. This latter was for logistical supply transportation purposes only and never for attack purposes. It was S.O.P. to have the LVT's back themselves into the ramp type craft and to be arranged in a very particular order so as to comply with the infantry attack plan. Amph-tracs are very sluggish afloat and do not handle with the ease or accuracy of screw driven craft. This characteristic often led to the LVT's crashing angularly into the hull of some vessel or pontoon barge when coming alongside, resulting in a sizable hole being punched through the hull just a few inches above the water line. On one occasion an amph-trac managed to pierce the hull of an LST to the depth of flooding a peak tank with salt water, to the great chagrin of the skipper and the troops aboard.

The personnel for the hastily organized LVT units were originally drafted from groups of men with specification serial numbers which might have some basic value in relation to the particular technical work required. Motor transport, tank, engineer, and communication personnel were the most adaptable to this program. As the courses of training progressed, however, fresh untrained men were put through these schools' courses, all selected on a criterion, quite high, based on their General Classification and Mechanical Aptitude Tests ratings.

A word about the "Armored Amphibian Tractors," popularly but erroneously referred to as "Amphibian Tanks." These vehicles are always designated as "LVT(A)," followed by the modification or model number. These craft were heavily armed but not as heavily armored as tanks. The first type as above indicated was equipped with a 37- mm. gun, later gyroscopically controlled; .50 and .30 machine guns mounted in various ways; some for anti-aircraft work perched atop an open turret, some behind splinter shields and some on a ball and socket swivel operated from within the craft proper. S.O.P. employed these craft in the very first assault wave to "hit the beach" ahead of the regular LVT's carrying the troops, in order to effect a heavy fire power against the beach defenses during that very tense and critical stage of an amphibious landing when all other firing, rocketing, and bombing has of necessity lifted from the littoral. That these craft paid their way in our revised concept of landing operations cannot be gainsaid. As above noted in the table much progress has been made in this type amph-trac. The 75-mm. howitzer which poked its snub nose out of its 3-inch armored turret plus the murderous automatic fire of these craft literally filled a hitherto unfillable gap.

As if never forgetting its birthright, one of the most outstanding uses of the amphibians during battles was constant supplying of food, water, medical supplies, and clothing to the front-line troops and the return cargoes of wounded men to the prompt attention of the medical collecting points and field hospitals. Several LVT's were detailed rigged as emergency field operating rooms for cases of utmost urgency.

During the years of peace to come it is earnestly to be hoped that this sea horse which won so many races will not be forgotten and relegated to pasture, but in view of its indispensability in assaulting coral-fringed targets, will continue to be groomed, trained, and improved as an insurance against the possibilities of an even greater race.

Immediately after graduating from the Naval Academy in 1936, Lieutenant Colonel Nohrden entered the U. S. Marine Corps. Becoming interested in amphibian tractors during their tests in 1940, he was assigned to the Amphibian Tractor Detachment, Dunedin, Florida, at first as Executive Officer and then as Commanding Officer. In 1944 he became Commanding Officer of the First Amphibian Tractor Battalion, Fleet Marine Force Pacific, and at present is at Okinawa.