Chieftain's Hatch: Ordnance Dept Tank Development

I hand over the keyboard today to a man who has been dead for over fifty years. Major General Gladeon Marcus Barnes was the Chief of the Engineering and Research Office of the US Army's Ordnance Department and as such, was responsible for the creation of the various weapons, including tanks, which the US Army fielded.

It would appear that in 1951, the Office of the Chief of Ordnance's historical branch sent a request to MG Barnes for assistance in the creation of the branch history documents describing Ordnance Branch's activities in WWII. As near as I can tell, his response hasn't been published elsewhere, I ran across them in the Archives in a recent trip. I provide them unedited, barring the odd obvious typographical error, and am not commenting on the contents here in order to allow you to form your own opinions untained by my own.



I am writing these notes on tank development during World War II from memory as an indication of how difficult it is to get any true picture of what actually occurred during this period from any official records . Similar remarks would also hold for any other important era of development such as for example, artillery. If the Ordnance Department is going to get a true story of the important developments of materiel during World War II it seems to me it would be necessary to get the personal experiences of the several officers who had the responsibilities of these various projects and then using these personal histories as background to fill in the voids from the official records .

Nearly every important development in materiel during the war was covered by an O.C.M. [Ordnance Committee Minute- Chieftain] and is thus recorded history. What is lacking from these official documents is the thinking which led up to these projects . The O.C.M. was the method by which the Ordnance Department kept the line of the Army informed as to what it was doing and obtained their concurrence as they went along. Thus it could not be said that the Ordnance Department branched off on its own without consulting the using services . It is not, however, generally understood that it was necessary for the Ordnance Department during this period to take the lead in the development of ordnance equipment. Each branch of the Army had a Service Board for testing equipment. Unfortunately, the officers of these boards ware not sufficiently experienced in the work of research and development to be of real help to the Ordnance Department except as a check on the final results which had been secured. Due to the fact that ordnance personnel spend their service careers in the study of ordnance materiel it is to be expected that their knowledge of weapons exceeds that of line officers whose careers are concerned with the tactical use of equipment.

It is not well understood that tactics are usually written around a particular weapon. Thus, field operations ordinarily do not generate ideas leading to new materiel. A new piece of equipment must first be produced, such as for example a machine gun, before the tactics can be devised for the exploitation of the capabil1t1es of the weapon. For these reasons it is necessary for the Ordnance Department to take a strong lead over the using services in the development of new equipment and then to get the help of those using services in determining where the weapon best fits into battlefield operations.


 Since I was in charge of the new tank development program for the United States Army in writing this history it is necessary for me to refer to actions which I personally took in regard to this program. I am not actuated from any motive of trying to bring out the importance of the part I personally played in this history but rather to explain exactly what did happen. It will be seen plainly that my statements are far different from the recorded history of tank developments in World War II.

In 1939 the Ordnance Department had worked out a tank known as the medium tank M2A1. This was the type of tank which was desired by the Infantry at that time. I might say that wag before the formation of the Armored Service and at that time the tank was considered primarily an infantry weapon. The M2A1 tank carried a 37mm gun in the turret and as I remember, some six machine guns. The 37mm gun was thought of as an anti-tank gun to protect the tank against other tanks but the real purpose of the tank at that time was thought of as a machine gun nest. Somewhere about 1940 or perhaps 1941 (I would have to look up the date) the Ordnance Department contacted Mr . K. T. Keller of the Chrysler Corporation asking them to manufacture the medium tank in quantity production for the Army, and in fact to build s new plant for that purpose - that plant is now the Detroit Tank Arsenal.

During 1939 the writer was assicned to the technical staff of the Ordnance Department and had conducted tests at the Aberdeen Proving Ground to determine the effectiveness against infantry of machine guns vs high explosive 75mm shells. These tests showed clearly that the 75 MM gun was much more effective against personnel at all ranges than machine gun fire.

 Mr. K. T. Keller went to the Rock Island Arsenal in 1940 to get the drawings for the M2A1 medium tank to be manufactured in the new plant and to start tooling . He obtained such drawings and went back to Detroit to go to work. In the meantime, the writer had been transferred to General Harris' office and made Chief Engineer of the Ordnance Department in charge of all research and engineering for the Ordnance Department . The writer visited Rock Island Arsenal and inspected the design of the M2Al tank. He returned to Washington and reported to General Wesson and General Harris that this tank was entirely unsuited for modern warfare. It could not survive on the modern battlefields due to lack of firepower. He further stated that the tank would be obsolete before it could be sent overseas. It would be necessary to introduce a 75mm gun into the tank if it were to be useful. He recommended that all work on the M2Al tank be immediately stopped and that an entirely new tank be designed. Although this meant stopping all work at the Chrysler Corporation this recommendation was approved by General Wesson and General Harris and the undersigned was authorized to design a new tank for the United States Army.

The writer wished to put the 75mm gun in the turret and entirely replace the 37mm gun. However, the using service which was still the Infantry at that time would not go along wlth the displacement of the 37mm gun. As a compromise, the best the writer could do was to leave the 37 gun in the turret and put the 75 MM gun in the sponson, opposite the driver. This tank so designed was called the M3 or General Grant. The Infantry demanded that the gun barrel not extend beyond the tracks. This shortened the gun and made it in reality a howitzer. It still was an effective weapon as compared with the 37MM gun which the Infantry retained in the turret.

The writer transfrrred the design of this tank from Rock Island Arsenal to Aberdeen Proving Ground and placed Colonel Christmas and Colonel Colby in direct charge. Later Colonel Christmas was re-assigned, leaving Colonel Colby in charge of this design. As soon as the design of the tank was completed it was successfully tested and approved by the Tank Board and put into quantity production.

The writer believing that the tank was still deficient in fire power immediately started the design of another tank on his own initiative. A high velocity 75mm gun was put in the turret entirely :replacing the 37 MM sun . In the meantime, experiments had been completed on welded armor and on the use of cast armor. This new tank was designated the M4 and later the General Sherman. A week or so prior to the completion of the design of the M4 tank General Jacob Devers was appointed in charge of the Armored Service. He was immediately contacted to come to Aberdeen Proving Ground and inspected the M4 tank to be completed. General Devers and members of his staff reviewed the  M4 tank and approved it making as I remember but one correction which was the position of the escape hatch.

 In the meantime, the Detroit Tank Arsenal had been producing the General Grant tank at a very high production rate as had several other manufacturers within the United States. The problem now was how to change from the General Grant to the General Sherman tank without losing production. This was successfully worked out so that while the production of the General Grant tank was continued its production was gradually decreased while the production of the General Sherman tank was increased as rapidly as possible until finally a point was reached where the manufacture of the General Grant tank could be discontinued altogether.

The importance or the 75mm guns in both the M3 and M4 tanks was quickly proven on the battlefield in Africa. The British had been driven back month by month by General Rommel until the Army had reached the outskirts of Cairo. The British Eighth Army was in a critical position. Appealing to the United States our Govermnent sent every available M3 and M4 tank to the British Eighth Army in Cairo. Luckily these tanks arrived before the battle of El Alamein. The arrival of the American tanks was kept a secret and the Germans did not know that the .British had received some 350 of those tanks. When the Germans attacked at El Alamein with their armored divisions they ran headlong into these American tanks with 75mm guns. As a result the German armor was destroyed, General Rommel was defeated and the British Eighth Army was saved. The lesson is, that if the M2Al tank had been manufactured as desired by the Using Services the battle of El Alamein would have been written differently in history.

In 1940 while the M3 tank was being designed the writer felt that the American Army should have a heavy tank mounting a more powerful gun and carrying thicker armor. For that reason the development of a new heavy tank for the Army was undertaken. This tank was to carry very heavy armor in front and due to the weight of this armor and the size of its armament the tank would be of the heavy class weighing in the neighborhood of 60 tons. Since it was desired to maintain the same mobility for the heavy tank as was possible with the medium tank the design required the use of a very large engine.

After study, the Wright Whirlwind engine of 1000 horsepower was selected. This introduced new tank problerms because no automotive vehicle at that time had used such a large engine and it was very doubtful whether a geared transmission could be built to carry the torque loads imposed. The writer called upon the Ordnance Automotive Advisory Committee composed of leading engineers from the automotive industry. Colonel H. Alden was Chairman of this Committee which was sponsored by the Society of Automotive engineers. As a result they recommended the development of three types of transmissions; electric, hydromatic and torque converter plus a two speed gear assembly. All these transmissions were built. The electric transmission which was designed by the General Electric Company proved an outstanding success. It enhanced the tank performance greatly and improved its cross-country mobility and maneuverability. The torque converter transmission with two speed drive was also successful although difficulty was encountered in the steering differential which depended upon the use of band brakes. This difficulty was later overcome, The first tank was was tested successfully at the plant of the Baldwin Locomotive Works the day after Pearl Harbor, 1941. The Ordnance Department was given an order for 3000 of these tanks and both General Motors and Baldwin Locomotive Works undertook tooling and production.  This tank project immediately ran into difficulty. Both the Army and the Engineer Corps opposed its use. The Engineer Corps had no bridge capable of supporting a tank of this weight. The Armored Service likewise was opposed to the use of a heavy tank feeling that the medium tank was superior for all around use. Unfortunately word of the heavy tank leaked out through the War Production Board and information concerning it was published in the newspapers. This was well ahead of the construction by the Germans of the tiger tank and it is quite possible that its  development was brought about by the knowledge that the American Army possessed a 60 ton tank. The writer equipped the heavy tank, which was known as the M6, with a very high velocity 3” gun. In fact, this gun was our high velocity anti-aircraft gun for which ammunition was available. At the time, it was believed that that this gun was of heavier caliber than any used by any country.

The writer feeling that a still heavier gun was necessary to face battlefield developments designed a new 90mm: gun. The gun made use of high strength alloys so that its outside diameter was no greater than that of the 3” gun it replaced. The new 90mm gun was successfully tested in the turret of the M6 tank.

In the meantime, the Army directed that the production of' the M6 tank be cancelled. The Army stated that due to lack of shipping space, it was much better· to ship two medium tanks M3 or M4 than one 60 ton heavy tank. In the meantime, production was stopped after the completion of some 44 of these tanks. The Army was thus deprived of the use of a heavy tank until the latter months of World War II . This nearly lead to a scandal as in the meantime the Germans had produced their famous heavy tiger tank, the armor of which was so thick that the 75mm gun in the M4 tank could not penetrate it.

Our troops in the European theatre gradually came to the realization that they were being out-gunned by the German tiger tank and that the 75mm gun in the M4 tank would not adequately defeat the armor of the German tiger tank. As the Using Services had turned down the heavy tank, I had studies made to find out what could be done to improve the fire power of the medium tank, M4. As a result of these studies the writer designed a new gun of greater fire power than the 75mm. This was the largest gun which could be placed in the turret of this tank without redesign of the latter. It worked out to be a high velocity 3" gun. Since the chamber of this gun had to be long and slender, due to the dimensional limitations of the turret, the chamber was different from that of any other 3” gunin service. Difficulties would occur in the field if another 3” gun were introduced with a different cartridge case. To avoid this I called this 3" gun a 76mm gun . It increased the fire power of the M4 tank but, of course, did not entirely bridge the gap between the 75mm gun and the 90mm gun.

In order to further increase the penetrating capability of the 76mm gun, high priority was given to a project for developing a special shell for the 76mmm gun, which would further increase its penetration. This round was based on the use of a tungsten carbide core, using an aluminum outer wall to surround the tungsten carbide and providing a steel base. This round gave increased penetration and was known as the 76mm HVAT round. As these rounds were manufactured they were transported by air to Europe and then to the Armored Divisions in the field. Thus each M4 tank ln Europe soon had a moderate supply of this special ammunition.

While the Services deprived themselves of the early use of the heavy 60 ton tank and 90gun a great deal of good for the services came out of this heavy tank project. I took the turret from the heavy M6 tank, lightened its armor and further lightened the armor of the M4 tank. A new type of vehicle for the Army was thus created. These vehicles were known as tank destroyers. They were lightly armored M4 tanks carrying 90mm guns in open turrets. Thousands of these tank destroyers ·were manufactured and sent to several theatres. Our troops were thus provided with a powerful tank destroyer capable of handling any German tiger tank encountered in the battlefield.

As soon as it became evident that it was impossible for the Ordnance Department to build the heavy tank M6 for the service the writer undertook the design of a new tank which would carry the high velocity 90mm gun designed for the M6 tank. It would be 1Jf a low silhouette so that the weight would be kept to about 40 tons with adequate armor. This project was immediately frowned upon by the Using Services and especially by General Leslie McNair who was head of the Ground Forces. The writer therefore went to General Brehon Somervell and explained to him the advantages of the new design and secured permission to complete the design and manufacture of a pilot tank. The pilot was completed

The writer arranged for an immediate tank test to be held at Aberdeen Proving Grounds. At this test armor plates of 3” and 4” in thickness were set up at an angle of 30 degrees to the vertical. The 4" plate corresponded to the thickness and angularity of the front of the tiger tank. Officers of the Army General Staff, Ground Forces, were invited to this test. The principal guests included Mr Stimson, Secretary of War; General Marshall, Chief of Staff; General Somervell, Chief of Supply Services, General McNair and General Moore and other officers of the Ground Forces; General Devers and high-ranking civilians and officers of the General Staff. Trenches were dug about 100' from the plates and the guests were invited to put on combat clothes including steel helmets and enter these trenches. A General Sherman tank at a range of 2000 yards first attacked the 3'' plate which it defeated. General Sherman was then fired against the 4" plate representing the front of the German tank. The ammunition bounced off this plate. The newly designed heavy tank with the 90mm gun, later known as the General Pershing, next attacked these plates. It successfully defeated the 3” plate and likewise defeated the 4” plate, all projectiles bursting behind the plate as required for tank destruction.

Taking a plane back to Washington from this test General McNair told the writer he would never approve a heavy tank, for the United States Army. This matter was taken up with Mr. Stimson and as the result of the day's test Mr Stimson and General Marshall approved the building of the new heavy tank. A large production program was given to General Motors Corporation.

The writer obtained permission to take the first 20 of the new tanks overseas to have them battle-tested. The writer visited General Eisenhower's headquarters at Versailles and obtained permission to introduce the 20 tanks upon arrival directly on the battlefield. General Eisenhower assigned these new tanks to the First Army and the 3rd Armored Division, commanded by the late Major General Maurice Rose who was shortly thereafter killed in battle. The tanks were demonstrated to the officers and the men of the First Army after a two-weeks training period. The tanks then went into action against the Germans. Wherever German tiger tanks could be found they were knocked out by the new American tank which was declared by General Rose to be exactly what the Army wanted.

The writer before returning to the United States visited all Army commanders in the field and acquainted them with the capabilities of the new tank. I found that all American Army commanders were alarmed over the situation resulting from the superiority of the German tiger tank. As a matter of fact, tank personnel were reaching a point where they were becoming afraid to fight in the M4 tank due to its lack of fire power. They received the new heavy tank with open arms and wondered why such a tank had not been available to them earlier. They did not realist that this was due entirely to the action of General McNair as Commander of the Ground Forces. The arrival of the General Pershing tank on the battlefield was most opportune and solved what would otherwise have been a very serious situation for our Army. In the meantime, tank production had been growing in the United States so that before the Armistice, some 3,000 of these tanks had been completed..

 It is gratifying that our troops in Korea have had a tank heavier than the M4. In the early days of Korea our troops were equipped only with American light tanks and during that period suffered heavily due to the fact that they were out-gunned by the Russian heavy tanks (T34). However, as soon as our heavy tanks arrived at the Korean battlefield the situation was reversed. General Collins has reported that American tanks have won every engagement. The General Patton tank is the General Pershing tank with some modifications.

In 1945 the writer designed a new heavy tank for the Army mounting a higher velocity 90mm gun, a still heavier tank mounting a 120mm gun and a new 155mm gun. All of these pilot tanks have now been completed and are being used as the basis for future new tank development for the Army.

It is hoped that these brief notes on tank development may help the writers of Ordnance history to better understand the recorded history of tank development during this period.


June 12, 1951

G. M. Barnes

Major General U. S.A. (Ret'd)

Discuss on Discord