And we’re back. In part one of this two part series we went over the M2 light tank and the
M3 Stuart and in part two we’re going to pick up exactly where we left off, so if you haven’t seen
that video already then now’s the time. The M3 Stuart was a great little tank,
and by early 1941 it was being built in its thousands in the US and then shipped across
the Atlantic to Britain and the Soviet Union through the lend lease program. The issue was,
as America started ramping up her aircraft production the need for petrol radial engines
grew rapidly – the same petrol radial engines that were being put into the back of the M3 Stuarts.
The Americans didn’t want Stuart tank production to hinder aircraft production or vice versa,
as they made the reasonable assumption that they’d probably need a lot of both in
the coming years. They also correctly assumed that during wartime they probably wouldn’t be
building as many cars as usual, meaning that automotive engines would be their best bet.
But the radials in the M3 Stuarts were far more powerful than any car or truck engine available,
so in June 1941 American engineers began testing if they could fit 2 Cadillac V8
engines side by side in the rear of the tank. And if you were using Cadillac car engines,
why not pair them with some Cadillac made automatic transmissions while you’re at it?
Each V8 engine was paired with its own Hydra-matic transmission, which then both fed into a transfer
case at the front of the vehicle, providing power to the wheels. So not only had those ingenious
Cadillac engineers solved the radial issue, but they’d also made the vehicle significantly easier
to drive. Fun fact – after the war Cadillac would advertise cars with this transmission
as being “battle-tested”. I mean, I’d buy it. A new hull was built on top of the new Cadillac
powertrain, sharing a lot of the improvements seen on the later M3A3 Stuarts such as the single
sloped frontal plate, the angled shoulder plates, and the hatches for the driver and co-driver.
It was notably different to the M3A3 though – the side armour was flat to allow for more interior
volume, and the designers had to add a hump to the back of the vehicle to put in radiators.
After all the M3’s engine was an air cooled radial, whereas the new tank had twin, water
cooled V8s, so the radiators had to go somewhere. The raised engine deck is probably the easiest
way to tell the vehicle apart from an M3, with the rest of the hull looking largely the same.
Inside, however, it was a different story. The change in engine allowed the driveshaft
to be mounted much lower, freeing up a lot of space below the turret and making
the vehicle a lot more comfortably to fight in. The hull was pretty much all new but the turret
and 37mm gun were carried over, with the tank mounting the same cylindrical turret as the M3A1.
The rest of the armament was identical to the M3A1, except for some very odd pre-production
models which had a fixed, centrally mounted machine gun in the middle of the hull. Safe
to say this didn’t make it to production. The new tank, known at this point as the M3E2,
entered testing at Aberdeen in the November 1941 – and the results were excellent.
The switch in engine and the added transmissions meant the E2 was just over a ton heavier
than a standard M3A3, and so the vehicle was slightly slower, but the advantages were huge.
The tank was incredibly easy to drive and to maintain, could use a lower temperature starter,
ran a lot quieter and boasted far superior crew comfort as well as survivability,
as the lower octane fuel used by the V8s made the tank a lot less likely to catch fire when hit.
The M3E2 was set to enter production as the M4
Light Tank. But, due to previous experience with M2 lights, M2 mediums, M3 lights and M3 mediums,
and the fact the M4 Sherman already existed, it was decided to call it the M5 to avoid confusion.
Production began in April 1942 and ran all the way until December,
with a total of 2075 M5 Stuarts being built. The reason production ended in December was
that an improved version of the vehicle had come along – the M5A1. In it’s simplest terms, the M5A1
mounted the larger turret of the M3A3 on the M5 hull. Bigger hatches, a bustle for the radio,
more room inside etc. But there were a lot of other more minor changes. Track grousers could
be attached to the side of the turret on these racks, a large stowage rack was added to the rear,
as escape hatch was added to the hull floor, and the .30 calibre anti-aircraft mount was
moved to the right hand side of the turret. Later, and still within the scope of the M5A1
designation, the pistol ports were removed, and an armoured shield was added to the side
of the turret. This shield provided a bit of protection for anyone operating the .30 cal,
but also meant that the gun could fold down out of the way when not being used.
Production of the M5A1 chugged along until June 1944, with 6810 vehicles built, more than 3 times
the production numbers of the standard M5. M5s and M5A1s would quickly begin to replace
the M3 Stuarts in British, American and Free French service, and would see action in Africa,
Italy, France and Germany as the Allies pushed through Europe. It had originally been planned
for the M7 light tank to partly replace the Stuart by mid-1943, but the failure of that
project meant that never really happened, and the M5 served until the end of the war.
The M24 Chaffee, a much better armed and armoured vehicle, arrived on the scene in
1944 and slowly replaced the M5s in service in the European Theatre. These vehicles were
shifted to the pacific, where the vehicle was still more than a match for Japanese
tanks still in action by that point in the war. After the war the M5 was used by the Chinese
alongside their M3s. Portugal used the M5 in their war in Angola, and both India and Pakistan
used the vehicle in the first Kashmir war. Sadly, unlike the M3, none are still in service today.
But there are plenty in museums all over the world if you do want to see one!
But the Stuart’s story definitely did not end with the M5. As we all know,
in armoured vehicle design, the question is always “How big a gun can I realistically get away with”,
and the Stuart was no different, especially as the effectiveness of the 37mm gun began to fade.
This had started as early as 1941, with the T18. This vehicle was an attempt to mount the M1A1 pack
howitzer, a 75mm artillery piece, into the M3 chassis. This was accomplished
by removing the upper half of the vehicle and putting on a large, cast casemate, with
the gun sticking out the front using a mounting developed from the 75mm mount of the M3 medium.
The T18 had pretty respectable armour and a pretty big gun for the time, but the historically picky
Ordinance Department weren’t impressed and rejected the vehicle in early 1942. And for
good reason – T18 was incredibly front heavy, had very poor vision and the limited gun traverse
angles made it quite impractical for a support gun. They knew that they could do a lot better.
In April 1942 two proposals were put forward – T41 and T47. T41 was for an open topped design,
not dissimilar to the M7 priest that had just gone into production.
This didn’t get very far at all before it was cancelled, as the T47, a turreted design,
was far superior. It did form, sort of, the basis for the T82, a much later design that mounted a
105mm howitzer in the Stuart chassis. It met the same fate as T41, however.
The T47 proposal involved removing the turret of the Stuart and replacing it with a much larger,
open topped model mounting the 75mm gun. The turret was a lot larger than even that of the
M5A1, and it was necessary to remove the driver and co-driver’s hatches on the turret roof.
Instead, the new vehicle had two smaller hinged plates on the front glacis,
which could be propped open when not in combat. These weren’t really big enough to use for access,
which had to be done through the turret. But this was acceptable, the vehicle wasn’t meant to be
getting shot at all that much anyway. The hull MG was also removed, likely due to that fact.
You’d be forgiven for thinking that this is the gun barrel – but it’s not quite. It’s actually
an anti-flash shield around the real gun barrel which is nestled inside like you can see here.
The turret itself was new, and unlike the M5 it was fully cast, with a more
rounded design. The vehicle would enter service in in late 1942,
as the M8 Howitzer Motor Carriage. Around 2 years later it would be sort of retroactively
named the M8 Scott after general Winfield Scott but it’s not clear how common this actually was.
The M8 was assigned to the HQ companies of medium tank battalions, for use as a support
weapon. It fought in Europe, Africa and the Pacific with the US Army and Marine Corps,
and saw large success, with its +40 degree elevation making it a very capable artillery
platform that excelled in the hilly terrain of Europe, especially in Italy.
The M8 would be phased out for the 105mm armed Shermans starting in early 1944, providing a
much bigger bang in a much more common chassis, especially as the M24 continued to replace the M5.
As I said, the M8 did see some action in the pacific. It’s turret also saw action,
mounted on a different chassis – the LVT. The LVT(A)-4 Amtank mounted the M8’s turret on a
fully amphibious hull, to provide fire support before, during and after an amphibious assault.
The French would receive a decent amount of M8s and LVT(A)-4s following World War Two, and would
use them in their ill-fated war in Indochina, modern day Vietnam. The M8 would stay in service
with the French until around 1962, seeing further service in their other ill-fated war in Algeria.
Clearly even an M5 Stuart with a 75mm gun on top can’t stop your colonies winning wars against you.
HOWEVER, how about an M8 Scott with an even bigger 75mm gun? This vehicle, the M8 Gun
Motor Carriage was an attempt to mount a 75mm M3 anti-tank gun in the chassis of a Stuart.
This vehicle is often referred to as the M8A1, but don’t let the fact it’s literally written on the
side fool you – this was never actually it’s official designation. Thanks again, America.
Since the M8 HMC already had a larger turret and turret ring, it was chosen as the guinea pig for
this new tank destroyer program. This project was given the green light in late 1942, as American
forces still had no fast tank destroyer type platform after the failure of the M7.
To fit the larger gun into the turret it was modified slightly,
with the turret extending farther back and the entire mantlet and gun mount being reshaped.
Apart from that though, very little was changed. The frankenscott was looking promising, and so was
submitted to the tank destroyer board for testing in February 1943. It was better off road than the
M3 GMC and better on road than the M10, and had all the benefits of the Stuarts that had come before.
That being said it also had a lot of the drawbacks – it was just too small to get
away with mounting that gun. The turret was so cramped that the crew were getting injured when
going over rough terrain, it couldn’t carry enough ammunition, and the driver could hardly see out.
The survivability was also questionable, since the hull crew didn’t have any hatches.
The lessons learnt on the M8 GMC would be used on the very successful M24 Chaffee and M18 Hellcat,
both mounting 75mm guns in relatively small chassis.
Aside from the M8s, there were no other significant variants of the M5 Stuart that
made into service. There were many failed designs, with a few mortar carriers and
self-propelled guns getting close to production but none quite making it.
There was even a calliope-esque prototype mounting 20 7.2 inch demolition rockets. But like the rest,
this was only ever a prototype. After all, there were much more capable platforms available.
The M5 did get a series of flame thrower variants however, and many were used as bulldozers,
with dozer blades attached to the front hull and the turret sometimes removed.
So, after these two videos you should be able to tell an M5 from an M3,
an M8 GMC from an M8 HMC, and chat to all your pals about which is your favourite. Unlikely.
What you can do is chat to other tank nerds on the discord, which is linked in the description.
Thanks very much to my patrons, and there are
plenty more videos on the way so make sure to subscribe, and if you enjoyed this video why
not leave a like down below. Thanks so much for watching, I’ll see you in the next one!