What makes a Heavy Tank a Heavy Tank

So before anything else, it’s important to have some sort of standard definition to refer to whenever we use the term “heavy tank”. With the lack of very many modern heavy tanks (most modern tanks are Battle Tanks, we’ll get to that later), we’ll have to develop our general case based on observations of World War II designs, where heavy tanks saw the most use. So, what does this give us?

Well, going by the design principals of the US, Germany, and the USSR, most heavy tanks had the following in common: First and foremost, heavy tanks had much thicker armor than their lighter counterparts. In WWII this could be as little as 50 millimeters thicker armor to armor that was 75 than 100 millimeters thicker than that of lighter tanks. 

German heavy tanks like this Tiger II had nearly seven inches of armor plating at points

This contributes heavily to the second major commonality – the role of these vehicles on the battlefield. While light and medium tanks were often used to fulfil tactical objectives (hunting enemy tanks, raiding supply convoys, routing small infantry units, and the like), strategic objectives were fulfilled by massing heavy tanks at a point, and then telling them to stay put or advance depending on their objective. Their armor was often thick enough that they could take multitudes of shots, even from other tanks, before even suffering drops in performance. This meant that a squad of heavy tanks was more than capable of holding a position more than long enough for reinforcements to show up, or could easily be used to spearhead and attack on an enemy and almost immediately split their ranks.

The third major commonality was in the armament – heavy tanks always had the biggest and best cannons available at the time. This went doubly true for the USSR who routinely mounted 75 millimeter, 105 millimeter, 122 millimeter, and 152 millimeter cannons on their tanks, especially their heavier tanks - the KV-2 in the background is an excellent example, sporting a 152mm howitzer for a main cannon. 

The fourth major commonality was their painfully low speed. With all their arms and armament, that didn’t leave much room for an engine, so heavy tanks tended to be considerably slower than their counterparts. In summation, our definition of a heavy tanks is lots of armor, big guns, strategic application, and low speeds. So now that we know what a heavy tank is, we can define what it isn’t.