The Steel Wedge: U.S. Marine Corps Armor in Pacific Island Combat

By Eric Hammel

Conceived as a visual record rather than a definitive history, The Steel Wedge is a substantial photographic archive—246 photos, many never before published—focused on the coming of age of U.S. Marine Corps tanks, tank destroyers, and armored amphibian tractors through the Pacific island-hopping campaign from earliest pre-war development to Okinawa in 1945.

A slice of the Marine Corps experience in the Pacific Theater during World War II, The Steel Wedge employs explanatory captions and narrative text to supplement its large and broad array of combat photographs. It is the first book ever to focus mainly upon this outstanding photographic record.

• Language: English
• Publisher: Pacifica Military History
• Release date: Feb 19, 2013
• ISBN: 9781890988487

Eric Hammel

The late Eric Hammel was one of America's leading military historians with more than 40 well-received books published over a 50-year career. His previous books on the Solomons campaign, Carrier Clash, Carrier Strike, Decision at Sea, and Starvation Island, are among the leading authoritative sources on the subject due to their extensive use of first-person testimony.

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Chapter 1

Marine Corps Tanks: A Beginning

The United States Marine Corps had a responsibility to provide the U.S. Navy with amphibious warfare expertise from its inception in 1775, an age in which soldiers of the sea served as the core of ad hoc landing forces composed mainly of sailors from the warships in which the Marines served. But it wasn’t until 1898, the year in which the United States first cast an imperial eye outward from its own shores, that the Marine Corps undertook a systematic program to build a real, modern amphibious warfare doctrine. The greatest effort took place in the 1920s and 1930s, and it reached completion just in time to be bolstered with the design and purchase of dedicated amphibious warefare equipment, much of it experimental and provisional, in 1940 and 1941.

The Marines well understood the power that the tanks and armored cars of the final pre-war decade could bring to a landing force composed mainly of infantry as it fought its way ashore, then out of a contested beachhead. But anything the Marines could dream of setting down upon a hostile beach had to be transported from ship to shore aboard landing craft severely constrained in size by the carrying and handling capacities of the troop transports and cargo ships that would lift a landing force from its base to that hostile beach. In the world of the late 1930s, only light landing craft could be lifted, and thus a safe journey from ship to shore could not be assured for even the lightest armored vehicles of the day, of which none could actually be carried without running the risk of its toppling into the sea or even tipping over the landing craft atop which it rode. Until larger, more powerful landing craft could be accomodated aboard transports and cargo ships—and really until large enough ramped landing craft could be developed and routinely deployed—any thought of landing armored vehicles, especially under hostile fire, remained but a dream.

This photograph, taken in the 1920s, amply illustrates the crude method of egress available to a relatively light artillery piece attended by a crew large enough to get it offloaded. Absent a large enough landing craft with a ramp strong enough to hold up to its weight and a shallow enough slope to prevent a damaging nosedive, there was then no effective way to get a wheeled or tracked vehicle ashore except over a strongly built dock or a stable landing stage. (Official USMC Photo)

The Marine officers who took part in completing work on amphibious doctrine through the second half of the 1930s were not blind to the advantages of getting tanks ashore beside their infantry and artillery, nor were they blind to the implications of meeting enemy tanks on distant beachheads. They were only stymied by a lack of adequate ship-to-shore movement, and so they looked at what might be reasonable solutions—light tanks and armored cars. This was at a time in which the much larger U.S. Army was only settling on an armored doctrine and attempting to settle upon armored vehicles it could afford and that American industry could build.

Long denied access to modern tanks due to a prohibition against a home-grown armor force imposed by a cavalry arm that was fighting (a losing battle) to remain relevant in modern warfare, the army nonetheless produced armored vehicles pretty much identical to what armored warfare enthusiasts would call light tanks but which a small cadre of forward-thinking American cavalrymen called combat cars to get around the prohibition on new tank designs. Following the fall of France in June 1940, armor stopped being a dirty word in cavalry circles, and a new armored force was hurriedly formed outside the cavalry arm but nonetheless around several mechanized cavalry regiments equipped with combat cars that were renamed and recharacterized as tanks. The Marine Corps, which had monitored developments in the army’s armor doctrine, asked for and received a small number of M2A4 light tanks, the first American-designed tracked armored vehicles to be armed with an antitank gun in a revolving turret. While the navy did what it could to design and build large enough ramped landing craft that its ships could carry and load, a handful of Marines went to work figuring out how and when lightly armed light tanks should be introduced on a hostile beach.

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Even though the Marine Corps lacked modern tanks in the mid and even late 1930s, it nonetheless had confidence that all the pieces would come together as the looming wars in Europe and the Pacific loomed closer and closer. Indeed, the Marine Corps’ first armor unit, the Experimental Tank Platoon, had been stood up in 1923, built around six World War I-era Renault light tanks. It took part in the 1924 fleet exercise at Culbera, off Puerto Rico, and in 1927, after being redesignated Light Tank Platoon, Marine Expeditionary Force, it was shipped to China to bolster Marine infantry units that were caught up there in Japanese-inspired unrest. Never used in combat, the tank platoon was shipped to San Diego in September 1928 and deactivated. Thereafter, budget constraints imposed by the Great Depression forestalled any move by Marine planners toward acquiring new tanks.

A break came in early 1937, when the Marine Corps was able to purchase, as test examples, five 5-ton Marmon-Herrington CTL-3 fully tracked, lightly armored vehicles whose most powerful weapon was a .50-caliber machine gun fired from a fixed forward position. The 1st Marine Tank Company was stood up at Quantico, Virginia, in March 1937, to work up a tank doctrine based on the Marmon-Herringtons. The gasoline-fueled CTL-3’s shortcoming were legion, and no adequate ramped landing craft was produced during this period, but the few Marines assigned to work with them were able to figure out some useful tactics. Thanks to input provided by Marine tankers, Marmon-Herrington produced five upgrade vehicles, dubbed CTM-3TBD, in late 1941. These diesel-powered vehicles were equipped with a pair of .50-caliber machine guns mounted in a rotating turret, but they were too little and too late; events had long since passed anything Marmon-Herrington would ever produce.

By the time the CTM-3TBD appeared, American industrial innovation had provided the U.S. Navy with the means to lift and load heavy landing craft and the Marine Corps with a ramped tank landing craft, the Landing Craft, Medium (LCM), with capacity to deliver a 15-ton light tank safely to shore. As the army’s armored force moved to the M3 light tank—an improved M2A4—the Marine Corps set its sights on acquiring cast-off M2A4s, of which the 1st Tank Company took possession of eighteen on August 1, 1940. In short order, the 3d Tank Company was activated at New River, North Carolina, and the 4th Tank Company was activated at Camp Elliott, California, near San Diego, to serve with the 1st and 2d Marine brigades, respectively.

A Marmon-Herrington CTL-3 machine-gun carrier. (Official USMC Photo)

A Marine Corps M3 light tank on maneuvers at Camp Elliott, California. Note the fixed sponson-mounted .30-caliber light machine guns on either side of the crew compartment. (Official USMC Photo)

There was as yet no amphibiouis armor doctrine; it was all self-taught Marine tankers could do to navigate from point to point on dry land. The M2A4 was fraught with hobgoblins: the drive shaft from the rear engine compartment to the forward drive wheels impeded the gunner and tank commander as the hand-cranked turret traversed, and there really wasn’t sufficient room for a four-man crew when the tank was buttoned up. And, of course, the narrow vision slits upon which crewmen relied when the tank was buttoned up severely restricted views to the point at which running off roads or tumbling down steep drops was commonplace. So was completely not seeing gunnery targets. But these were complaints made by all tankers of the age.

A U.S. Army M2A4 light tank prepares to disembark from an LCM ramped landing craft during joint army–navy exercises at New River, North Carolina, in August 1941. Note the M2A4’s distinctive muzzle brake beneath the gun tube. (National Archives and Records Administration)

A 2d Tank Battalion M3 light tank based at Camp Elliott, California, in 1941. (Official USMC Photo)

An expanding Marine Corps and a steady march toward war caused the tank establishment to expand in mid 1941. Ahead of a move to stand up the 1st Marine Division at New River and the 2d Marine Division at Camp Elliott, the 3d and 4th Tank companies were redesignated Company A, 2d Tank Battalion, and Company A, 1st Tank Battalion, respectively. The divisions were activated on May 1, 1941; the 1st Tank Battalion was activated on November 1, 1941; and the 2d Tank Battalion was activated on December 20, 1941. By then, Marine tanks and tankers were serving overseas.

Two platoons and headquarters of Company A, 2d Tank Battalion, were shipped with the 1st Provisional Marine Brigade to Iceland during the summer of 1941 as a means to free up the island nation’s British garrison for war duty. At the time, both platoons were equipped with twelve M3 light tanks. The brigade returned to the United States in March 1942.

Each tank battalion of the day was built from four light tank companies equipped with M2A4s or M3s, and a headquarters-and-service company. Also, each division’s reconnaissance company was assigned administratively to the tank battalions and designated Company E.

Small groupments of light tanks were also provided on an ad hoc basis to some of the Marine defense battalions charged with guarding island bases in the Pacific. A platoon of five light tanks was based at Midway and an unknown small number was at Johnston Island. During the spring of 1942, a company of tanks from each division accompanied each of two Marine brigades that shipped out to defend American Samoa and British Samoa. The old Marmon-Harringtons also found their way to Samoa.

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While a large and growing number of Marines were working through the details of delivering tank support to infantry units undertaking amphibious assaults in distant places, a second armored weapons system was sneaking into the Marine tables of organization and equipment. The second system had two precursors.

Since 1898, for as long as modern Marines had been actively seeking an amphibious offensive doctrine, they had been working on the means to deny their enemies success in mounting their own amphibious assaults and counterassaults. They had invented stand-alone Marine defense battalions that in later years typically fielded antiarmor, antiboat, and antiaircraft protection for coastal areas open to assault. As well, they had, on February 16 and March 1, 1942, stood up the 1st and 2d Special Weapons battalions, respectively, as organic units within the two operational Marine divisions. These special weapons battalions were nothing more than smaller, lighter defense battalions, each with an antiboat, antiair, and antiarmor component. Each special weapons battalion fielded a battery each of 90mm and 40mm dual-purpose antiair/antiboat guns, and three antitank batteries, each composed of six wheeled 37mm antitank guns and two mobile 75mm anti-tank guns. It was the last of all, the 75mm antitank guns, that constituted the Marine division’s second armored component.

Marmon-Herrington light tanks serving with the 1st Separate Tank Company in American Samoa in 1942. The 2d Separate Tank Company, deployed in British Samoa, had a similar collection of Marmon-Herringtons, including numerous variants manufactured in very small numbers. In the end, all of the Marine Corps’ approximately forty Marmon-Herrringtons were abandoned in Samoa and the two separate tank companies were reequipped with tanks suited to World War II combat conditions. (Official USMC Photo)

The system the army designated the M3 75mm Gun Motor Carriage (GMC) was a marriage of convenience. Advances in artillery had led the United States to convert from the venerable Franco-Prussian War-era 75mm field gun (known in the United States as the French 75) to the more power ful and longer ranged M101 105mm field howitzer, which completed development at the Rock Island Arsenal between 1928 and 1936 and began coming into service in large numbers in 1941. Thus, the United States owned a considerable number of French 75s, and tens of millions of 75mm artillery rounds, it had no real use for.

Marine Corps SPMs take part in crew training in California. (Official USMC Photo)

At the same time, the development of a medium tank by American ordnance designers had run afoul of American industry’s temporary but no less ennervating inability to produce a cast tank turret sufficiently large to mount a 75mm main gun and sufficiently robust to absorb the shock of firing a 75mm high or even medium-velocity tank round. The result was a sidetrack in the development of armor doctrine that produced a mobile 75mm antitank gun system quite separate from tanks themselves. Following a German lead, the U.S. Army developed the M3 halftrack to move armored-infantry troops into battle alongside tanks, a mutually beneficial arrangement. With plenty of French 75s on hand, and given the delay in producing a large, robust tank turret, and then with thousands of M3 halftracks flooding out of factories, a few bright men created the 75mm GMC to serve as a stopgap antitank weapon capable of defending American light tanks on battlefields that might otherwise be dominated by German medium tanks armed with 75mm tank guns.

The Marines acquired a small number of 75mm GMCs, which they dubbed self-propelled mounts (SPMs) and doled out to the antitank batteries of their defense-oriented special weapons battalions. In addition to antitank defense, the SPMs could provide artillery support with relatively high-angle fire, but they each carried only fifty-nine rounds, and most of those by far were antitank rounds.

It was thus that the Marine Corps went to war in late 1941 with a little more than one hundred M2A4 and M3 light tanks and no more than a few dozen antitank SPMs.

Official USMC Photo

Chapter 2

Guadalcanal

Marine tanks did not get into action in the new Pacific War until August 8, 1942, the second day of the six-month-long Guadalcanal Campaign. And for all that there were a dozen major land battles over the course of that mighty effort, Marine tanks got into action only three times, and peripherally at that. Marine SPMs from the 1st Special Weapons Battalion engaged Japanese forces only once.

The landings by the main body of the reinforced 1st Marine Division at Guadalcanal commenced on the morning of August 7 against nil opposition, but Marines found plenty of action about forty miles to