What is a Third-Generation Main Battle Tank?

Those following the news these days--and its repleteness with reference to tanks as the war in Ukraine continues to escalate--may have noticed the term "main battle tank," and along with it, reference to "third-generation main battle tank."

They may also have been left unclear as to what "third-generation" means in this context--even after trying to research the matter online.

As it happens this is not without reason. Consider the generations, and some of their better-known examples:

1st generation: M47 Patton, Centurion, T-54
2nd generation: M60 Patton, Chieftain, AMX-30, Leopard 1, T-62
3rd-generation: M1 Abrams, Challenger, Leclerc, Leopard 2, T-80

Looking from the tanks in one generation to those in the next one easily notices quantitative changes--the later tanks tending to have more powerful engines and tougher armor and bigger guns than their predecessors. (For example, the M47 had a 90 mm gun, the M60 a 105 mm gun, the M1 a 120 mm gun.) Still, these tell one only so much. (The original edition of the third-generation M1 did have a 105 mm, while the second-generation Chieftain had a 120 mm weapon too.)

Moreover, the qualitative changes are not terribly easy to discern--in part because the changes in propulsion and fire control and firepower were less profound than in, for example, jet fighters during the same period, nothing that happened with tanks between the '40s and '90s as dramatic as the shift in design features, and performance in the design of those aircraft. Aerial combat, after all, saw a shift from subsonic turbojet-powered planes armed with fixed machine guns the pilot aimed by pointing their plane at their target to stealthy supercruise-capable turbofan-powered planes able to engage several at once with internally carried radar-guided air-to-air missiles with hundred mile ranges. By contrast tanks went from being internal combustion engine-powered, metal-hulled vehicles firing shaped-charge and "sabot" shells from the big gun on their turret to punch through a particular thickness of steel from a kilometer or two or three away to fifty years later . . . being somewhat larger and heavier internal combustion engine-powered, metal-hulled vehicles still firing shaped-charge and sabot shells to punch through a somewhat greater thickness of steel from a slightly greater distance somewhat more accurately. (Indeed, even the caliber of guns did not change so much, with World War II and early post-war-era heavy tanks like the Soviet IS-2 and IS-3, and British Conqueror, packing guns of 120 mm+, while some "tank destroyers" packed adapted heavy artillery to the anti-armor role, with one version of the IS-3 having a 152 mm caliber far larger than anything any main battle tank uses today.)

Indeed, where between the '40s and the '90s there were five generations of jet fighters (the last taking to the air with the F-22), in the 2020s third-generation main battle tanks remain the standard in the world's armies.

In fairness this slowness of change in the state of the art was not for lack of trying on the part of tank designers, who did try out a good many new concepts. However, those they did experiment with were rarely embraced in a wide and consistent way, as with an automatic loader for the tank's gun, or missiles to be fired from the tank's launch tube. Some armies embraced them--with the Soviet army making auto-loaded, missile-launching guns the norm for their main battle tanks from the T-64 forward. Others generally eschewed these technologies, with (after its experience with the Shillelagh missile) the U.S. an example, the M1A1 Abrams still having a human loader for a gun that fires only shells, not missiles. Thus did it also go in the area of propulsion, with some embracing more powerful gas turbines, but others sticking with more fuel-efficient and easier-to-maintain diesel engines (the M1A1 using the gas turbine, the Leopard 2 a diesel, and Soviet/Russian tanks using one or the other, with T-64s and T-80s using the turbine, the T-72 the diesel). And so on and so forth.

All of this makes generalization from one generation to another unsatisfying on many a point. Still, one can point to a few developments that are associated with each crop.

The replacement of the earlier division into light, medium and heavy tanks with one balanced, do-it-all type of main battle tank itself was itself the big innovation in the first generation.

The second generation saw some improvements in what was still basically analog fire control (like the first image-intensifying night vision sights, the first laser-range finders, the increasingly standard use of at least a mechanical ballistic computer), and "NBC (Nuclear, Biological, Chemical) protection"--specifically the design of the tank so that the crew could be sealed up in it and supplied with purified air if the tank is in an area subject to nuclear, biological or chemical attack.

The third generation retained the NBC protection, of course, but saw fire control go digital (with ballistic computers increasingly electronic rather than mechanical, and advances like thermal imaging). Armor also saw a significant change, with the earlier reliance on rolled homogenous steel armor giving way to "composite" armor combining plates of different material (so that there were layers of steel mixed with layers of ceramic material to provide more "stopping power"). And for what it is worth one certainly finds all these in the Abrams, the Challenger and the other tanks to which the label is presently being applied.