M4 Shermans of Tokyo Ordnance Depot

United States of America (1950)
Medium Tank – Unknown Number Refitted

With the start of the Korean War in June 1950, the US military’s workhorse tank of the previous conflict, the Medium Tank M4 Sherman, was once again called into service. This included employing M4 equipped units stationed in Japan, as well as scavenging working vehicles and arms left over from the Pacific Campaign of the previous war, in an action designated Operation Roll-Up. By this point in time, and in the eyes of the US, the Sherman was becoming a bit long in the tooth. Nonetheless, M4s of multiple types and variants acquitted themselves admirably during the conflict in the ‘Land of the Morning Calm’. These included regular gun tanks, flame throwers, and dozer tanks.

As well as the everyday stresses and strains of combat, tankers had to deal with the harsh mountainous terrain of the Korean Peninsula, which took its toll on the Army’s tanks. For example, between July 1st 1950 and January 21st 1951, the US military lost 338 tanks to mechanical failure and 51 tanks to terrain alone. Luckily, the American forces had a relatively local means of repairing and refitting tanks at an industrial scale located in Japan. The Tokyo Ordnance Depot, located in the Jūjō district of Kita, Tokyo, became the regional hub for the refit and repair of tanks, armored vehicles, and trucks during Operation Roll-Up. This leads to the remarkable figure that 45% of tanks, 82% of armored cars, and 75% of artillery pieces fielded in the Korean War by the US consisted of equipment recovered during Operation Roll-Up.

Although a forgotten part of a largely forgotten war, the Tokyo Ordnance Depot played a key role in Operation Roll-up, as well as equipping and mobilizing American Armored Units in the early stages of the first major war since the culmination of the Second World War. Almost every type of tank then in service with the US Military passed through the Tokyo Depot at one point or another, be it M4, M24, M26, M45, or M46. However, it was the old reliable Sherman that flooded the factory floors in the summer of 1950 that the depot really left its mark on.

The Tokyo Ordnance Depot

Located in the north east quadrant of Tokyo, the Tokyo Ordnance Depot (東京兵器庫, Tōkyō heiki-ko) had a long history of manufacturing weapons and ammunition. In the Meiji period (1862 – 1912), it became home to the Tokyo Artillery Arsenal. It was later renamed the Tokyo Arsenal, and became home to the First and Second Army Arsenals. With Japan’s capitulation on September 2nd 1945, the Second World War finally came to an end, and a period of American occupation began in the Japanese islands which lasted until 1952. At this time, the US Army moved into the Tokyo Arsenal, turning it into a hub for vehicle and weapons maintenance. Under the occupiers, it became known as the Tokyo Ordnance Depot (which for the ease of reading, will be shortened to ‘TOD’ throughout this article).

The main US garrison of the depot was made up of the 8160th Army Unit, Tokyo Ordnance Depot, which worked alongside Japanese civilians. In total, about 11,500 people worked at the Depot at its peak of activity. With the outbreak of the Korean War in June 1950, the workload of the Depot vastly increased but the number of personnel stayed the same. At one point, this even led to localized strikes by the Japanese workers.

Although part of the occupying force, the US 8160th soon became a beloved part of the wider community in the area. The unit even sponsored a local orphanage in Akabane, and made an effort to encourage the employment of local people. Local children from schools and orphanages were frequently invited on tours of the base, to show good will to an objectively defeated and war-weary nation.

At the end of the 1950s, the US began to slowly withdraw its military presence from Japan, with part of the Depot being given back to the Japanese people. This would become the Jujo Garrison of the fledgling Japanese Ground Self-Defense Force (JGSDF). Much of the area was still occupied by US military installations, however, and during the later Vietnam War, it became the home of the Oji Camp and Field Hospital.

Background of the M4 Series

The M4 series of tanks is undoubtedly one of the most recognizable vehicles to come out of the Second World War. Starting life in 1941 as the T6, it was later serialized as the M4. The British named it ‘Sherman’ after William T. Sherman, General of the Union Army in the American Civil War. The tank officially entered service in 1942 and saw its first action at the Second Battle of El Alamein that October/November with the British 8th Army under the Command of, then Lieutenant-General, Bernard ‘Monty’ Montgomery. Throughout its service life, the M4 went through countless upgrade programs spawning multiple variants. Each variant would employ either a new engine, a new suspension system, or a new main gun.

The majority of M4s to go through the Tokyo Ordnance Depot were of the M4A3 type, but a few older M4s and M4 ‘Composites’ also passed through its doors. The M4 was the standard all-welded model of the tank, while the ‘Composite’ was produced with the early runs of both the M4 and M4A1, featuring a mostly welded hull combined with a cast upper glacis. Hence, it is a ‘Composite’ or ‘Sherman Hybrid’, as the British Army called it. M4s and M4 Composites featured the original, inconveniently large Continental Radial engine. This engine produced 350 or 400 hp and had to be mounted vertically in the tank, resulting in the characteristically deep hull of the M4s. As the Sherman ‘base model’, the M4 went on to be used in almost every theater. It was generally armed with the 75 mm M3 gun, but also came armed with the 105 mm M4 howitzer as the M4(105). Only a relatively limited number of Composite/Hybrid M4s were built by the Chrysler Corporation, the total being just 1,676. As such, most of this version of the tank were never upgraded, and retained the original 75 mm gun (save for the British Sherman Ic Firefly), Vertical Volute Spring Suspension (VVSS), as well as other early Sherman features.

The M4A3 was a later and probably most well known version of the M4 which could be considered the ‘definitive model’. The standard model A3 entered service towards the end of 1942, and had an all-welded hull, the standard VVSS suspension, the short 75 mm gun, and a more reliable Ford GAA V8 Engine. Later in the war, it would often be equipped with the newer, wider E8 Horizontal Volute Spring Suspension (HVSS), which lowered the vehicle’s ground pressure. The later A3 models came with the new, larger T23 turret carrying the 76 mm M1 tank gun, but remained available with the older, smaller turret armed with the 105 mm M4 howitzer. The M4A3 came quite late to the Second World War, but it did see action. Called up once more for the Korean War, the M4A3(76) HVSS was the most common Sherman type to see action. That being said, variants based on it also served in smaller numbers, such as the howitzer-armed M4A3(105) HVSS and the unique double-barreled M4A3 ‘POA-CWS-H5’ HVSS howitzer/flamethrower tank.

In the decades after World War 2, the Sherman series has been done a great disservice by both professional and amateur historians alike. Unfounded claims that they were all but useless against German armor, and instantly burst into flames when hit persist to this day. These fallacies have endured thanks largely to poor representations in films and video games. In reality, while it did struggle in the early days of its service, the Sherman was one of the best all-around tanks of the War. The tank was easy to adapt, easy to repair, and available in high numbers. By the end of the war, almost 50,000 Shermans had been built. Their service post-war was not limited to the US. Dozens of countries around the globe used a Sherman in one of its many variants at one point or another, with many staying in service into the late 20th century, and a few veterans reaching the 21st.

Part of the M4 series’ success was its great adaptability. It was the base for a wide range of other vehicles, from tank destroyers and self-propelled guns to flamethrowers and engineering vehicles.

Operation Roll-Up

In the early post-WW2 years, substantial budget cuts and wide-spread demobilization resulted in a poorly equipped, poorly maintained, and poorly manned American Far East Command (FEC) and Japanese Occupation Force. General Douglas MacArthur even complained about this directly to US military leadership, claiming that this state of affairs compromised the US’ ability to defend Japan and Korea. MacArthur’s foreshadowing fell on deaf ears, as the US did not see the peninsula as strategically important at this time. So, Operation Roll-up, brought into effect before the Pacific War had ended, was revitalized. This operation consisted of ‘roll-up teams’ traveling between the Pacific Islands, assessing US military equipment left scattered across the islands. Small arms, trucks, artillery, and most importantly, tanks were all sat unused, effectively seen as surplus. It then fell to the catchily named Foreign Liquidation Commission (FLC) to disperse this surplus material amongst the war-ravaged Pacific Islands and nations. As well as Japan, the Philippines, China, and Korea were either sold this surplus or received it as aid. In 1947, it is estimated that nearly 1-million tons (1.15 m tonnes) of military equipment had been sold to the Philippines alone. The Operation began to stagnate and proceed at a leisurely pace in the late 1940s. For example, just 200,000 kg (203 tonnes) of material was shipped to Japan in 1949. Even so, the Operation was expected to be wrapped up by June 30th 1950.

This changed on the morning of June 25th 1950. With the North Korean People’s Army (NKPA) effectively “blitzkrieging” their way south through the Korean peninsula, the US and its allies had to mobilize rapidly to reinforce South Korea’s Republic of Korea Army (ROKA). With the capital, Seoul, lost early on, US troops were ordered into action by the United Nations in early July. This initial US contingent was mustered from the Japanese Occupation Force and the US 8th Army which was stationed in Japan. It was clear that this force would be bearing the initial brunt of combat over the summer months. Despite best efforts, they were under-equipped for warfare. The first American armor deployed in Korea was the M24 Chaffee. While an excellent light tank, it was ill-suited to facing the NKPA’s T-34-85s that had been instrumental in the taking of Seoul. It was clear better tanks were needed. While reinforcements were requested from the United States, it would take time to muster the man and armored power. In more recent years, this initial lack of available Armor has become known as ‘The Korean Tank Panic’, and resulted in the expedient development of the M47 Patton II, although it arrived too late to serve in the war. As a result of this lack of tanks, Operation Roll-Up, 5 days before it was due to come to an end, was expedited. Arms and armor began flooding into the Tokyo Ordnance Depot.

‘Tinkering’ in Tokyo

An estimated 8,000 vehicles of all types passed through TOD between July and August 1950, but it was the Sherman that the Depot really left its mark on. As well as the expected maintenance or fixing of engines, replacing damaged suspension units, and various other fixes, the personnel sought to improve the M4 where possible. Efforts were made to increase the M4s self-sufficiency, especially taking into account the effect of Korea’s terrain on armored vehicles. All tanks of this type received the addition of specific stowage which included space for spare suspension components, track links, and sprocket flanges. It was hoped that carrying such components would allow tank crews to make repairs themselves, instead of relying on, or waiting for, dedicated recovery teams.

The layout of the stowage was akin to that of the M32 Armored Recovery Vehicle (ARV), also based on the M4 tank. Simple brackets were fabricated and installed on the front corners of the hull sides to carry the spare sprocket flanges, while copious amounts of track-links were stored along the flanks. Lastly, crescent brackets were installed on the turret cheeks that could carry spare roadwheels. These were standard stowage modifications equipped on both older ‘small turret’ M4s and newer T23 turret M4s. It is these modifications that make it easy to identify any M4 tank that was refitted at the Tokyo Ordnance Depot.

Rarer Refits

As well as the standard refits to M4 and M4A3 HVSS models, some rarer M4 types passed through TOD. One of these was the M4 Composite. This rarer type of M4 was only used by the US Army during the Pacific Campaigns. Directly after the war, along with other equipment, they were often dumped in the ocean rather than be returned to the US, although a few were likely sold to various Pacific and Southeast Asian nations. This is because, in October 1948, VVSS models of the M4 (including Composites) and M4A1 (75 mm and 105 mm) were classified as Limited Standard and were “unsuitable for meeting U.S. requirements but satisfactory for meeting foreign-aid requirements”.

The personnel at the Tokyo Ordnance Depot took these ‘unsuitable’ M4s and turned them into dozer tanks by equipping them with the standard M1 Dozer Blade.

The addition of the M1 Dozer Blade necessitated the addition of a hydraulic ram assembly to the transmission housing, and mounting brackets on the second suspension unit. Seemingly rather mundane, dozer tanks were in high demand throughout the Korean War. They were frequently used to clear or widen narrow mountain trails and push through road blocks.

Perhaps most crucially, dozer tanks were used to cut firing slopes. These were used by regular gun tanks to increase gun elevation for indirect fire missions, allowing shells to be lobbed onto targets at higher angles. This usage only increased as the war progressed and both sides dug in.

An even rarer modification was made to an unknown number of M4A3(75)s. This consisted in replacing the 75 mm M3 gun – long outdated at this point in time – with the more lethal 76 mm M1 gun. The M1 Gun was probably sourced from tanks too damaged in other respects. It is unclear whether TOD personnel were trying to replicate the failed M4A1 (76M1) project of the early 1940s, or took inspiration from the M4A1E6 and M4A3E4 refit programs which were underway state-side for the Mutual Defense Assistance Program (MDAP) – if they were even aware of this at the time. Either way, both the M4A1 (76M1) and MDAP tank projects basically achieved the same result, although the MDAP result was far more successful.

Placing the larger 76 mm gun in the ‘small’ M4 turret was never an easy task, as can be seen in the early M4A1 (76M1) efforts. While the gun did technically fit, it made the already cramped space of a turret interior even less spacious. Second to this, it made the turret imbalanced, meaning excessive wear on the horizontal traverse gear. It was suggested that an 800 lb (362 kg) counterweight be added to the back of the turret. When the turret was retested with the additional weight, it was found that it suitably rebalanced the turret, allowing the existing gears to work. The gun had a vertical traverse range of -12º to +25º in the standard M34A1 gun mount. Other modifications were introduced. A new front plate for the turret was developed, incorporating a spacer that moved the gun forward approximately 2 inches (50 mm), granting more room around the breech end of the gun. Counterweights were also added to the recoil guard to properly balance the gun to allow proper operation of the original gyro-stabilizer.

While the Ordnance Branch was pleased with the arrangement, the Armored Force did not endear to it, claiming that the little amount of space left in the turret was simply impractical and that the project represented a poor ‘quick-fix’ to allow for rapid production. With this, the project was canceled in May 1943.

The idea was revisited for the M4s of the MDAP program. The US, not wanting to send its best hardware abroad, retained newer components, including the larger T23 turret designed to carry the 76 mm gun. Essentially, the turrets for the M4A1E6 and M4A3E4 were modified in the same way as the earlier ‘76M1’ project, with the addition that the radio was moved out of the turret into the sponsons. Both the E6 and E4 would see quite a career in various armies across the world from Denmark to Yugoslavia, and India to Pakistan.

While the end result of the Tokyo refit is visually similar, it is important to express that there was no connection between it and the tanks of the MDAP project. Just how much of these projects were replicated is unknown, as is how many tanks were converted in this way by the Tokyo Depot. It is also unknown if this was just a one off experiment, or if any of them made it to Korea. Short of a few external photos of the same vehicle at the Tokyo Depot, no other visual evidence of this particular refit exists, with further information just as rare.

A smaller refit of note was made to the M4-based M7 Howitzer Motor Carriage (HMC). An issue that had followed the M7 through its service life was the relatively shallow maximum elevation angle of the 105 mm howitzer, originally just +35º. In the last war, this resulted in the vehicle having to be parked on a ramp to achieve greater arcs of fire, and this was doomed to be repeated in the mountainous terrain of Korea. To combat this, the Tokyo engineers modified it to allow +67º. This modification would later be standardized on the M7B2.

Action in Korea

Activated in Japan on July 17th 1950, the 8072nd Medium Tank Battalion received 54 of Tokyo Depot’s rebuilt M4s, consisting mostly of late-model M4A3s with HVSS. Under the command of Captain James H. Harvey, A Company of the 8072nd arrived at Pusan on July 31st. From there, on August 1st, they moved via rail to Masan. The 1st Platoon was then sent to reinforce the 19th Infantry at Chungam-Ni, while the 2nd Platoon was sent to reinforce the 27th Infantry near Chindong-Ni. By August 2nd, the 1st and 2nd Platoons of A Company were in combat, marking the first shots of the M4 Sherman’s second major war, just under five years since the end of its first.

Barring a few M26 Pershings lost at Chinju on July 31st, the M4s were the first American medium tanks to see combat in Korea. On August 4th, the rest of the 8072nd and their M4s arrived at Pusan, just in time for the 8th Army to re-designate them the 89th Tank Battalion on August 7th. By this time, other armored units were rolling in from the United States. By the end of August 1950, over 500 tanks were deployed in Korea. This included a battalion equipped with the new M46 Patton, but the vast majority of the armored force still consisted of older M26s or M4s of various ilks.

The M4 marched ever onward in its second war. Compared to the M26 and newer M46, the M4 was lighter, had a better power-to-weight ratio, and was far more mobile over the rocky terrain and narrow trails of the Korean hills and mountains. The M4 remained the most common tank deployed in Korea throughout the war, all the way through to the armistice in 1953. When Allied forces finally broke through the Pusan perimeter in late September 1950, it was the M4s of the 89th leading the charge. Staying at the head of the Allied push, the M4s were the first tanks to cross the 38th Parallel and reach the Manchurian border. In the later stages of the conflict, as the fighting slowed, M4s were used as mobile artillery and were favored in the role of bunker busting – especially the 105s. Post-war, the M4 continued to serve in a peacekeeping role, before being officially declared obsolete by the US in 1956.

Conclusion

In addition to providing material support to the US military’s campaign in the Korean War, Operation Roll-Up was advertised to both the US Government and US people as a cost-saving measure, with estimates that per-unit costs being just 50% to 95% of a new build. It is estimated that the operation saved approximately US$8 billion, with the Army claiming a large part of that was made up of saving rubber from tires alone. The Tokyo Ordnance Depot is a forgotten part of Operation Roll-up and the Korean War effort as a whole, despite playing such a crucial role at its outset. The 8072nd/89th would not have had the armor to bring to bear against the North Koreans had it not been for the efforts of TOD’s 8160th Army Unit and Japanese Civilian workers. Unfortunately, with a forgotten war comes forgotten people. Hopefully, this article goes someway to highlighting the importance of these forgotten folks’ role.

Many of the M4s used in the War would return to Japan, with a lot of them handed over to the Japanese Ground Self-Defense Force (JGSDF). Damaged tanks were also returned to the depot, where they were scrapped. This links the TOD with one of Tokyo’s most famous landmarks, the Tokyo Tower, officially 日本電波塔, Nippon denpatō, (“Japan Radio Tower”). The scrapped tanks were melted down and turned into the steel girders used in the Tower’s lattice-work construction, based on the Eifel Tower. Construction began in 1957, with a third of the steel used sourced from US tanks scrapped at the TOD. When the tower opened in late October 1958, it was the tallest free-standing structure in the world.

The Tokyo Ordnance Depot and the land on which it sits was officially handed back to the Japanese Government in 1971. The Jujo Garrison of the JGSDF is still stationed here, although much of the surrounding land has been repurposed into community buildings, schools, and parks.

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Sources

R.P. Hunicutt, Sherman: A History of the American Medium Tank, Presidio Press, 1978

Simon Dunstan, Armour of the Korean War 1950 – 53, Vanguard No. 27, Osprey Publishing, 1982

Jim Mesko, Don Greer, Armor in Korea, A Pictorial History, Squadron/Signal Publications, 1984

Michael Schaller, American Occupation of Japan: The Origins of the Cold War in Asia, Oxford University Press, 1988

John W. Dower, Embracing Defeat: Japan in the Wake of World War II, WW Norton & Co, 2000

Peter S Kindsvatter, Operation Rollup: The U.S. Army’s Rebuild Program During The Korean War, University of Pennsylvania Press, 2007

Jerry Ravino and Jack Carty, Hearts of Iron: The Epic Struggle of The 1st Marine Flame Tank Platoon: Korean War 1950-1953, Turner Press, 2011

Patrick Stansell, Son of Sherman, Vol. 1, The Ampersand Group, 2013

Anthony Tucker Jones, Armoured Warfare in the Korean War: Rare Photographs from Wartime Archives, Pen & Sword Books, 2013

Raymound Giuliani, Sherman In The Pacific War 1943-45, Histoire & Collections Publishing, 2015

History.army.mil: Chapter III: National Defense and the United States Army, Chapter V: Emergency Conditions, Emergency Measures, Chapter IX: Eighth Army in Command

Pierre-Olivier Buan, Joe DeMarco and Leife Hulbert, Sherman Minutia (1) (2)

www.nichimyus.jp