Armored Avenger: The Legacy of the M10 GMC
The M10 GMC was the first main tank destroyer developed and used by the United States and many of its allies. I have always found great interest in this vehicle, mainly due to the nature of its development. It saw usage from Operation Overlord onward to the end of WWII. Since this is the first American tank I’ve covered, I decided right after Independence Day was a great time to cover it. Many people also know it by the nickname “Wolverine”; however, there is no evidence of this nickname ever being used by U.S. forces, and its origin is debated.
In the wake of the German force’s encounters with Soviet T-34s and KV-1s in 1942, they upgunned the Panzer IV and turned the Stug III into a tank hunter. At this point, the U.S.’ best tank destroyer was the T12 GMC, a conversion of the M3 half-track armed with a 75mm gun. This design proved ineffective due to the limited traverse of the weapon and its overall slow mobility. The need for an effective tank destroyer led the top brass of ordnance to search for a more effective and fully-tracked chassis in the M3 Lee and the M4 Sherman. Development with the M3 Lee chassis eventually led to the M7 Priest SPG, and development with the M4 led to the M10 GMC. This program also led to the creation of the tank destroyer force and a significant change in doctrine.
The change in doctrine entailed battalions of fast-moving tank destroyers that could quickly respond to enemy tanks encountered by other units. This was in contrast to many other countries at the time, who opted for heavier tank destroyers that were well-armed and armored. Germany's doctrine, for example, relied more on having the armor to take shots frontally and shoot back with an effective gun. German tank destroyers were usually built onto an obsolete tank chassis to make it functional again. U.S. doctrine aimed to use the already-built chassis’ to create something effective and mobile without designing a specialized vehicle.
The original prototype for the M10 GMC was on the chassis of the M4A1 and armed with a 3-inch M7 naval gun. This was a decided success, and eventually, the production M10 was built on the M4A2 chassis. The production M10 had several differences from the chassis it was built on, including modified side armor that was more sloped to allow for slightly better effective armor for the hull. The M10 featured an open-top turret with distinct counterweights mounted to the rear of the turret to balance the gun. Approximately 5,000 were produced at the GM Fisher tank arsenal in Grand Blanc, Michigan. There was one variant of the M10, the M10A1, with the main difference being it was built on the M4A3 chassis and was equipped with a Ford-made gasoline engine. The Ford plants produced 1700 M10A1s, and the last 300 were fitted with the more advanced M1 76mm gun, which had higher muzzle velocity and could fire heavier ammunition. One proposed origin for the nickname “Wolverine” that I have found is due to the original plant in Michigan. Michigan is known as “The Wolverine State” and has been for many years, so it’s hypothesized that PR releases from GM may have referred to the vehicle as “Wolverine.” The only other theory I’ve seen is that model companies and video games may have popularized the nickname.
The M10 was successful in combat overall, and crews found the nature of the vehicle advantageous. This was due to U.S. Army doctrine, which states that infantry often supported tank destroyers like the M10. The open-top turret allowed for accessible communication with troops on the ground and easy dismount in the case of an emergency. The M10 first saw combat in Tunisia in early 1943 and was more than a match for the German tanks deployed there. By 1944, their speed and firepower were insufficient in most cases, where they were supplemented with the M36 Jackson armed with the 90mm and the far more agile M18 Hellcat. The vehicle was still in service well into 1945 despite the fact they couldn’t reliably deal with the more advanced big cats of the Germans. The shortcomings of the M10 led to a trend seen with many U.S. tank crews during the war, with makeshift armor being added to many vehicles to supplement the often inadequate armor against German guns. The makeshift armor came in the form of sandbags and timber attached to the front and sides of the hull, and some crews made makeshift roofs from the armor of knocked-out tanks.
The M10 is a fascinating look at the unique tank destroyer doctrine of the U.S. Many other countries opted for casemate tank destroyers, where the gun could only face the same direction as the hull and had limited traverse. This doctrine had advantages and drawbacks, mainly because many turreted tank destroyers were open-top to accommodate a larger gun. It was very effective in the field, even with the reduced survivability.