Several different warfare strategies were developed between the two world wars. According to one of them - it will clearly show its effectiveness in the future - tanks were to become the main striking means of the army. Thanks to the combination of running and fire qualities, as well as with the help of good protection, this technique could break into enemy defenses and move relatively quickly deep into enemy positions, having insignificant losses. The only weapon class that could fight armored vehicles was artillery. However, with great firepower, it had insufficient mobility. Something was needed that had both good armor penetration and sufficient mobility. Anti-tank self-propelled artillery mounts became a compromise between these two things.
First attempts
In the United States of America, the creation of self-propelled anti-tank gun mounts began almost immediately after the end of the First World War. True, the then self-propelled guns were unsuccessful - there was no talk of any adoption. The topic of anti-tank self-propelled guns was remembered only in the mid-thirties. As an experiment, the 37 mm field gun was modified: its caliber increased by 10 mm. The recoil devices and carriage were redesigned so that the gun could be placed in an improvised wheelhouse on the chassis of a light M2 tank. The car turned out to be original and, as it seemed to its creators, promising. However, the very first tests showed the inconsistency of the rework of the gun. The fact is that an increase in caliber led to a decrease in the relative length of the barrel, which ultimately affected the initial velocity of the projectile and the maximum thickness of the pierced armor. The self-propelled artillery mounts were again forgotten for a while.
The final return to the idea of a self-propelled tank destroyer took place at the very beginning of 1940. In Europe, the Second World War had been going on for several months, and overseas they knew very well exactly how the German troops were advancing. The main offensive means of the Germans were tanks, which meant that in the very near future all countries that could be drawn into the conflict would begin to develop their armored forces. Again the idea arose to create and bring to mind an anti-tank self-propelled gun. The first option to increase the mobility of the 37 mm M3 cannon was simple. It was proposed to make a simple system for attaching the gun on Dodge 3/4 ton series cars. The resulting T21 SPG looked very, very unusual. Before that, only machine guns were installed on cars, and the guns were transported exclusively using towing devices. Still, the main problem of the new "self-propelled gun" was not unusual. The car chassis did not have any protection against bullets and shrapnel, and its dimensions were not enough to accommodate the entire crew and a sufficient amount of ammunition. As a result, the experimental prototype of the improvised self-propelled gun T21 remained in a single copy.
They tried to adapt a 37 mm anti-tank gun to a jeep several times, but the limited dimensions of the body of an all-terrain vehicle did not allow placing in it also a calculation with ammunition
As of 1940, 37mm anti-tank guns were still a good enough argument against enemy armor. However, in the very coming years, an increase in the thickness of the armor and its resistance to shells was to be expected. For a promising tank destroyer, the 37 mm caliber was insufficient. Therefore, at the end of 1940, the creation of a tracked self-propelled gun with a three-inch gun began. The design of the Cleveland Tractor Company tractor, which was used as an airfield tractor, was taken as the basis for the new machine. A gun with a shield was installed in the rear of the reinforced chassis. The 75 mm M1897A3 cannon, dating back to the French design of the 19th century, was slightly modified taking into account the peculiarities of operation on a self-propelled chassis. Now it was called T7. The self-propelled gun itself received the designation T1. The firepower of the new self-propelled gun was impressive. Thanks to its good caliber, it could be used not only against enemy armored vehicles. At the same time, the T1's undercarriage turned out to be overweight, as a result of which technical problems arose regularly. Nevertheless, the military-political situation in the world was rapidly changing and the situation required new solutions. Therefore, in January 1942, the new ACS was put into service under the designation M5 Gun Motor Carriage. The military ordered 1,580 M5 units, but actual production was limited to only a few dozen. The chassis of the former tractor did not cope well with the new loads and tasks, it needed to be significantly changed, but all work in this direction was limited to only minor modifications. As a result, by the time it was ready to start large-scale production, the US Army had newer and more advanced self-propelled guns. The M5 program has been phased out.
M3 GMC
One of those vehicles that put an end to the M5 self-propelled gun was an artillery mount based on the brand new M3 armored personnel carrier. In the fighting compartment of the half-tracked vehicle, a metal structure was mounted, which at the same time served as a support for the gun and a container for ammunition. The support cells housed 19 shells of 75 mm caliber. Another four dozen could be packed into boxes located in the rear of the ACS. The M1897A4 cannon was placed on the support structure, which could be aimed horizontally at 19 ° to the left and 21 ° to the right, as well as in the sector from -10 ° to + 29 ° vertically. The M61 armor-piercing projectile penetrated at least 50-55 millimeters of armor at a distance of a kilometer. The installation of a fairly heavy cannon and stowage for ammunition on an armored personnel carrier had almost no effect on the driving performance of the former armored personnel carrier. In the fall of 1941, the self-propelled gun was put into service under the designation M3 Gun Motor Carriage (M3 GMC) and launched into series. In almost two years, more than 2,200 units were assembled, which were used until the end of the war.
The T-12 tank destroyer was an M-3 Halftrack half-track armored vehicle armed with a 75 mm М1987М3 gun
In the battles on the Pacific Islands, the M3 GMC showed good abilities in the fight not only against tanks, but also against enemy fortifications. With regard to the former, we can say the following: Japanese armored vehicles, possessing not very serious protection (the armor of the Chi-Ha tank had a thickness of up to 27 mm), when hit by a projectile, the M1897A4 cannon was guaranteed to be destroyed. At the same time, the American self-propelled guns' own armor could not withstand the 57-mm shells of the Chi-Ha tanks, which is why there was no obvious favorite in the battle of these armored vehicles. At the very beginning of mass production, the M3 GMC received several design innovations. First of all, the bulletproof protection of the gun crew was changed. Based on the results of trial operation of prototypes and the first production vehicles in the Philippines, a metal box was installed instead of a shield. Some of the M3 GMC self-propelled guns were able to survive until the end of World War II, although the proportion of such vehicles is small. Due to the weak protection, which could not withstand the shells of most field and even more anti-tank guns, in the last months of the war more than 1300 self-propelled guns were converted into armored personnel carriers - this required dismantling the cannon and its support, stowing shells, and also moving fuel tanks from the rear of the vehicle in the middle.
Based on General Lee
Despite its considerable combat experience, the M3 GMC self-propelled gun was originally supposed to be just a temporary measure in anticipation of more solid vehicles with serious reservations. A little later, the development of the M3 GMC began two projects, which were to replace it. According to the first, on the chassis of the light tank M3 Stuart it was required to install an M1 howitzer of 75 mm caliber. The second project involved an armored vehicle based on the M3 Lee medium tank, armed with an M3 cannon of the same caliber as in the first version. Calculations showed that a three-inch howitzer, located on the chassis of a light tank "Stuart" could successfully fight not only with tanks and enemy fortifications. Significant recoil would also be enough for a fairly quick incapacitation of its own chassis. Project "Stewart" with a howitzer was closed for hopelessness.
T-24 was an "intermediate version" of a tank destroyer
The second SPG project, which was based on the M3 Lee tank, continued under the designation T24. By the fall, the first prototype was built. In fact, it was the same "Li" tank, but without an armored hull roof, without a turret and with a dismantled sponsor for the native 75-mm cannon. The running characteristics of the self-propelled gun were no worse than those of the original tank. But with the fighting qualities there was a whole problem. The fact is that the mounting system for the M3 gun was made on the basis of existing equipment for anti-aircraft guns. In view of this "origin" of the support system, aiming the gun at the target was a complex and lengthy procedure. Firstly, the elevation of the trunk was regulated within the range of only -1 ° to + 16 °. Secondly, when the gun was turned for horizontal guidance, the minimum elevation angle began to "walk". At the extreme points of the horizontal sector with a width of 33 ° in both directions, it was + 2 °. Of course, the military did not want to get a gun with such intricacies and demanded to remake the ill-fated unit. In addition, criticism was caused by the high height of the car with an open top of the wheelhouse - once again no one wanted to risk the crew.
In December 1941, at the suggestion of the commander of the ground forces, General L. McNair, the Tank Destroyer Center was opened in Fort Meade. It was assumed that this organization will be able to effectively collect, generalize and use the experience gained regarding the appearance and operation of anti-tank self-propelled guns. It is worth noting that General McNair was an ardent supporter of this direction of armored vehicles. In his opinion, tanks could not fight tanks with all possible efficiency. To ensure the advantage, additional armored vehicles with solid armament were required, which were the self-propelled guns. In addition, on December 7, Japan attacked Pearl Harbor, after which the United States had to increase funding for a number of defense programs, which included anti-tank self-propelled gun mounts.
The chassis of the M-3 tank, which was used to create the T-24 tank destroyer, served as the basis for the T-40 self-propelled gun. The T-40 tank destroyer differed from its unsuccessful predecessor in a lower silhouette and a more powerful weapon. According to the test results, the T-40 self-propelled gun was put into service under the designation M-9
By the beginning of 1942, the T24 project had been significantly redesigned. By rearranging the internal volumes of the tank chassis, they significantly reduced the overall height of the vehicle, and also changed the mounting system of the gun and the gun itself. Now the horizontal guidance angles were 15 ° and 5 ° to the right of the axis and to the left, respectively, and the elevation was adjusted in the range from + 5 ° to 35 °. Due to the shortage of M3 cannons, the updated self-propelled gun was supposed to carry the M1918 anti-aircraft gun of the same caliber. In addition, the chassis design underwent several more changes, due to which it was decided to issue a new index to the new ACS - T40. With the new gun, the self-propelled gun almost did not lose in combat qualities, but it won in the simplicity of production - then it seemed that there would be no problems with it. In the spring of 42, the T40 entered service as the M9. Several copies of the new self-propelled gun have already been built at a plant in Pennsylvania, but then the leadership of the Center for Tank Destroyers said their word. In his opinion, the M9 had insufficient maneuverability and speed. In addition, it suddenly became clear that the warehouses did not have even three dozen M1918 guns, and no one would allow their production to be resumed. Since there was no time for the next revision of the project, production was curtailed. In August 42, the M9 was finally closed.
M10
The M9 ACS was not a very successful project. At the same time, it clearly showed the fundamental possibility of converting a medium tank into a carrier of heavy artillery weapons. At the same time, the military did not approve of the idea of a tank destroyer without a turret. In the case of the aiming angles of the T40 self-propelled guns, this turned into the impossibility of firing at a target moving perpendicular to the axis of the gun. All these problems needed to be solved in the T35 project, which was to be equipped with a 76 mm tank gun and a rotating turret. The M4 Sherman medium tank was offered as a chassis for the new self-propelled gun. For simplicity of design, the tower of the M6 heavy tank, equipped with the M7 cannon, was taken as the basis for the armament complex. The sides of the original turret were reshaped to simplify production. More serious work had to be done on the armored chassis of the M4 tank: the thickness of the frontal and stern plates was reduced to an inch. The front of the tank was not changed. Thanks to the weakening of protection, it was possible to maintain mobility at the level of the original "Sherman".
The experience of fighting in the Philippines clearly demonstrated the advantages of the rational tilt of the armor plates, as a result, the original hull of the Sherman tank, which served as the basis for the creation of the T-35 tank destroyer, had to be redesigned. The self-propelled gun, which had a hull with sloped sides, received the designation T-35E1. It was this machine that was put into mass production under the name M-10.
At the very beginning of 1942, the first prototype of the T35 self-propelled gun went to the Aberdeen Proving Ground. The fire and driving performance of the prototype satisfied the military, which could not be said about the level of protection and ease of use inside the cramped tower. During the beginning of tests from the Pacific Ocean and from Europe, the first reports began to come about the effectiveness of the inclined arrangement of armor plates. This know-how attracted the attention of the customer in the person of the American military department, and he did not fail to write the corresponding item into the technical requirements for the self-propelled gun. By the end of spring 42, new prototypes were built with a rational slope of the side plates. This version of the self-propelled guns, named T35E1, turned out to be much better than the previous one, it was recommended for adoption. By that time, a new proposal of a technological nature had been received: to make an armored hull from rolled sheets, and not from cast plates. Together with the hull, it was proposed to redesign the turret, but it turned out to be not so easy. As a result, a new structure was created without a roof, which had a pentagonal shape. In late summer, the 42nd T35E1 entered service as the M10, and serial production began in September. Until the end of the next 1943, more than 6,700 armored vehicles were built in two versions: for a number of technological reasons, the power plant was significantly redesigned in one of them. In particular, the diesel engine was replaced by a gasoline one.
A number of lend-lease M10 self-propelled guns were delivered to the UK, where they received the designation 3-in. SP Wolverine. In addition, the British independently modernized the supplied M10s, installing their own cannons on them. 76mm QF 17-pdr. Mk. V gave a tangible increase in the efficiency of fire, although they required some modifications. First of all, it was necessary to significantly change the design of the gun mounts, as well as weld additional protection onto the armor mask of the gun. The latter was done to close the gap formed after installing a new gun into the old mask, whose barrel had a smaller diameter than that of the M7. In addition, the British gun turned out to be heavier than the American one, which forced the addition of counterweights to the rear of the turret. After this modification, the M10 received the designation 76 mm QF-17 Achilles.
M10 tank destroyer armed with a 90mm T7 cannon on trial
The M10 was the first type of American SPG to receive both good armament and decent protection at the same time. True, combat experience soon showed that this protection was insufficient. So, the tower open from above often led to large losses of personnel when operating in forests or cities. Since no one was involved in the problem of increasing security in the headquarters and design bureaus, the crews had to independently take care of their safety. On the armor were sandbags, track links, etc. In the front-line workshops, improvised roofs were installed on the tower, which led to a significant reduction in losses among the crews.
ACS M10 "Wolverine" (M10 3in. GMC Wolverine) of the 702nd battalion of tank destroyers, knocked out by German artillery on the streets of Ubach, Germany. The serial number on the front of the car is painted over by the censor
ACS M10 "Wolverine" (M10 3in. GMC Wolverine) 601st tank destroyer battalion of the US Army on the road to Le Clavier, France
Rehearsal for the landing on the sandy beaches of a battalion of M10 tank destroyers and several companies of infantry at Slapton Sands in England
A camouflaged M10 tank destroyer of the 703rd Battalion, 3rd Armored Division, and an M4 Sherman tank are moving through the crossroads between Louge-sur-Maire, La Bellangerie and Montreuil-aux-Ulm (Montreuil-au-Houlme)
M10 fires in the Saint-Lo area
An M10 from the 701st Panzer Fighter Battalion moves along the mountain road in support of the 10th Mountain Division, which is advancing north of Poretta into the Po Valley. Italy
