Today, I am not at the Tank Museum at Bovington
but I was invited there in 2017 to 2019 and I finally wanted to put some photos and footage to
good use, so let us look at the M3 Medium Tank, also known as the Grant and Lee by
the British depending on the variant. At first, you might notice it looks a like a cross
between an M4 Sherman and the French Char B1 bis. The chassis is very similar to the Sherman, but
you have all these rivets like on the Char B1 and that tiny turret on top of that chassis and
then the large gun mounted in the right front of the chassis. The similarity to the Char B1 bis is
not without irony, if we consider the fact that: “Design of the new M3 medium tank began in
July 1940 in the wake of the French defeat.” As such the M3 is a bit of modernized antique,
it combines modern features like reliability, mobility. and mass production compatibility
like cast parts. Yet at the same time antique features like rivets, multi-turrets, large
size and large crew. The reasons for this were that it was rushed into production, since
the fall of France came as quite a shock: "The collapse of France in 1940 had caused an
enormous shock throughout the world. In the USA most Americans did not want to believe that the
Germans had won, and the French were defeated.” As such the US Army wanted a modern medium tank
sooner rather than later. The main requirements were a strong frontal armor of at least
2 inches (so about 5 cm) and a 75mm gun that could fire a high-explosive round.
“On 13 June 1940, the characteristics of a tank incorporating the updated
requirements were outlined in OCM 15889. The new vehicle was standardized on
11 July 1940 as the medium tank M3.” Now, most tanks that were rushed into production
like the Panther usually had a multitude of teething problems, similarly this was not only a
problem the Panther faced, the British had quite many problems with their own tanks as well:
“The British tanks of the period were notoriously unreliable and suffered
unacceptably high breakdown rates.” Yet, the M3 did not face these problems,
according to Zaloga it was far more reliable than contemporary British designs. Well, the
reason for this was the industrial capacity and experience of the United states, the M3
used improved versions of previous US designs. “As a result, by the time the M3
medium tank entered production, vigorous testing had wrung most of the
bugs out of the automotive components.” At the same time, in other areas there
was a certain lack of experience, most notably when it came to the engine
design and welding. As you can clearly see, there are a lot of rivets on the tank. You
don’t want rivets since if they get hit, their counter-part inside the tank might turn
into shrapnel that hits your crew. Now, not all variants of the M3 Medium Tank had rivets, but
quite a lot did, so what is the reason for this? “Although industry widely used welding at
the time, welding of armor plate presented a significant challenge. Very hard armor steel with
a high carbon content posed a real problem because the welds did not withstand shock very well and
would crack when hit by an enemy projectile.” At the same time, you see quite a lot of round
and complex shapes here. These are cast parts, generally cast steel provides less armor
protection than welded armor plates, yet, there are no welds that can be a weak point
and additionally the rounded shape can provide protection as well. For more information check
out my Tank 101 – Armor protection video on this. Casting has the other benefit
that it reduces production time: “The M3 medium tank was the first mass-produced
American tank to use a cast turret, and many other components were cast as well. It took
far less time to cast a complex structure than to fabricate it out of multiple plates of steel,
making casting attractive under the time pressures imposed by the war. On the other hand, American
industry had limited casting capacity […].” One major challenge for mass production was
the lack of proper engines and/or sufficient supply of them, this was also a major issue with
the M4 Sherman tank. The reason for this were: “No obvious commercial sources existed since
tank engines had to be significantly more powerful than truck engines and at the same time
much smaller than ship and locomotive engines. As a result, the auto plants came
up with some ingenious solutions.” Now, you might wonder, the chassis almost
looks like a Sherman and the Sherman has this nice turret with a 75mm or in some cases
even a 105 mm gun. So why does the M3 medium tank does not have a proper turret, I mean
the Germans and British all had plenty of properly mounted turrets at that time, so why
this weird construction on the right front? “Ordnance had no experience building
turrets capable of housing a 75mm gun. They were not certain how large the turret
ring would need to be to withstand the recoil forces and had not developed a recoil system
compact enough to fit inside a tank turret. In addition, they were leaning toward the use of
a cast-steel turret to speed up tank production, but industry had yet to prove the ability
to manufacture such a large armor casting.” Furthermore, Hunnicutt notes that
many design problems of a sponson mount for such a gun had been
already fixed with the T5E2, which looks a bit like a M7 Priest or
a M3 Grant without the centered turret. It was suggested by the Armored Force to only
produce the M3 in limited numbers and once a solution for a turret with a 75 mm gun was found,
it should be changed. There was only one problem: “However, the urgent need for large quantities
of new tanks, particularly by the British in the Middle East would not permit the interruption
of the production plans already in progress.” Which brings us to the British part of the M3
Medium Grant and Lee story. The British wanted the US industry to produce their own tanks
like the A12 Matilda and the A15 Crusader. Yet, as this was not going to happen, the
Americans presented them with the M3 medium: “Regarding the M3 Medium they [the British]
were particularly unhappy with the fighting arrangements in general and specifically they
objected to the location of the radio set. In fact there was little about the
tank that they did like. In the end it was only American agreement that the
British might have some concessions, like the design of the turret and some
modest changes to the fighting compartment that tipped the balance – that and
the fact that there was really no alternative.” (Fletcher, David; Zaloga, Steven J.:
British Battle Tanks: American-made World War II Tanks. Osprey Publishing: Oxford, UK, 2018, p. 46)
So, what were the main differences? As you can see here, on the left is the American
M3 and on the right the British. The British turret was slightly lower, yet wider.
Additionally, it did not fit a machine-gun cupola on top. Furthermore, “only” a 6-man crew was
required instead of the 7 of the US design. Since in British version the radio was in
the turret and the loader of the 37 mm gun served also as a radio man. Note that Hunnicutt
mentions that later the crew was changed to 6 men, although he does not specify if
this refers British version or not. These different designs are also the reason
for the different names given to the variants: “The British designation for their version of
the M3 was the General Grant I. The standard U.S. model was referred to as the General Lee I. It
was obvious which one they considered the winner.” Yet, there are two caveats to this, first
the British also received 1347 M3 tanks in the Lee configuration. And more importantly:
“British units seldom distinguished the Grant and Lee, generally labelling both types
as ‘Grants’ regardless of the turrets.” Let us take a short look at the
main armament or better armaments. In the turret was the 37mm gun, it was
meant to be used against tanks. Although, when the tank was used in the jungles
of Burma, the 37mm with canister rounds was used to against trees and foliage to
eliminate camouflage of Japanese troops. “Initially, the 75 was considered as support
artillery and not as the primary antitank weapon, so there was little or no concern about muzzle
velocity or armor piercing performance.” Initially, there were some solid steel rounds
issued, but those tended to break when they hit face-hardened armor plates. There were also
some issues with the sights as well. Ironically, the first proper armor-piercing ammunition
was captured German rounds mated with American cartridges. According to Fletcher and Zaloga,
the first proper armor-piercing ammunition were improvised from captured German ammunition of
the short barreled 75mm gun from the Panzer IV. Later the 75mm gun was replaced
with a longer barreled one, which also provided a higher muzzle velocity
thus improving the armor piercing capabilities. So, let us look at strengths and weaknesses.
One major problem the British faced in the desert against Rommel was the combination of
German combined arms particularly anti-tank guns, anti-aircraft guns in the anti-tank role
and tanks together, in contrast to the British combination of cruiser and infantry tanks.
“[…] British cruiser tanks were armed first with the 2-pounder and later the 6-pounder guns. Both
of these had excellent anti-armour performance, but did not offer a high-explosive punch.”
This was particularly a problem when engaging anti-tank guns, since they were
very small and required a direct hit or a sufficiently large blast.
“The Grant offered an antidote to the anti-tank gun threat, since it could fire an
effective high-explosive projectile that had a much greater chance of disabling an anti-tank gun
even without a direct hit. The Grant’s 75mm gun was also effective in the anti-tank role, and
was supplemented by the 37mm gun in the turret, which offered performance similar
to the British 2-pounder tank gun.” Another benefit as already mentioned
was the reliability. Furthermore, the M3 Medium tank could take a serious beating:
“One Grant had been hit no fewer than 31 times, with the only damage being caused by two 50mm hits
on the front visors and a rear hit by a 37mm gun.” Although, like any other tank at that time, it was
no match for the Flak 88 with anti-tank rounds. Yet, there were also some drawbacks. The obvious
one was that the 75mm gun had a limited traverse, but its position also prevented the tank
from being used in proper hull down position, since well, if your gun is mounted
in the hull, you can’t use it when you cover your hull. The dual-gun
configuration had another drawback as well: “The dual 37mm/75mm armament was a distraction
to the commander because it was difficult to concentrate on more than one target at a time.”
The large size, especially the height was a major issue as well, especially in the rather
flat desert. At times the height was a benefit for better spotting, but generally the
larger you are, the more flak you gonna catch. Now, let’s briefly touch the variants.
The M3A1 had a single casting for the hull superstructure instead of a riveted
design. The M3A2 used a welded hull, whereas the M3A3 used a welded hull and
a diesel engine. Then there was the M3A4, which used a multi-bank engine combining 5
bus engines together. Then there was the M3A5 which used rivets and a diesel engine.
Let us take a short look at production, series production started in June
1941 and ended in December 1942. According to Zaloga a total of 6258 M3 Medium
were built. 1660 of these used the British turret, which is a bit less than 27 %.
“During the course of production, a variety of incremental improvements were
undertaken across the entire M3 family. British reports indicated that the side
doors were susceptible to spall damage, so an escape hatch was added to the belly and the
hull doors welded shut. In the final production runs, the hull doors were completely absent.”
Well, I hope you liked this episode. Thank you to Andrew for reviewing the script.
Big thank you to the Tank Museum at Bovington for inviting me in 2017, 2018 and 2019, at the
first trip I also recorded my top 5 tanks there, so you might want to check that one out.
As always sources are listed in the description. I hope you enjoyed this episode,
thank you for watching and see you next time.
