For a good 10 years before the war, German doctrine recognized that high-velocity, flat-trajectory antiaircraft guns could be used in an antitank role in emergency situations. In North Africa, the Germans quickly discovered that their 88 mm flak guns were devastatingly effective against British tanks. The Soviets, meanwhile, also believed that the enemy's infantry, rather than its tanks, should be the primary target of Soviet tanks. In 1942, therefore, the Soviets revived the German World War I practice and assigned an antitank role to all artillery weapons. By the final two years of the war, Soviet gun production rates widely outmatched that of the Germans, and the balance tipped in favor of the Soviets.
Most armies used field artillery crews to man antitank units. As the war progressed, antitank guns became larger and more powerful, and many were mounted on self-propelled (SP) carriages to give them mobility equal to the tank. The Germans on the Eastern Front pioneered the use of SP antitank guns in an offensive role. The Soviets also developed a wide range of SP weapons. As the war progressed, the distinctions blurred among the Soviet Union's field, assault, and antitank SP guns. Almost all American SP antitank guns were turret-mounted, but the Germans and especially the Soviets favored turretless vehicles. They were simpler and cheaper to build, and the lack of a turret produced a lower profile that made the vehicles smaller targets.
The Soviets spent the first two years of the war on the defensive, and as a result they mastered defensive AT tactics. At Stalingrad, they deployed four sets of antitank belts to a depth of 6.2 miles. Soviet tanks only counterattacked after all forms of their artillery had stopped the German tank attack. The tactics the Soviets developed at Stalingrad were refined and applied with devastating effect later in the Battle of Kursk, the graveyard of the German panzers.
The U.S. Army organized AT guns into tank-destroyer (TD) battalions. In 1942, a TD battalion had three companies of three platoons of four guns each, either towed or self-propelled. American SP tank destroyers did not do well in North Africa. The operational area was too vast for the guns to mass effectively, and the terrain was too open for the SP vehicles to find good defensive hull-down positions. Many American commanders shifted to the British system of towed antitank guns, but these proved far less effective when combat operations later moved to Western Europe. In that more restricted terrain, the towed guns moved too slowly, and they were too close to the ground to shoot over the hedgerows. By July 1944, the U.S. Army started reequipping all TD battalions with SP guns, but some units still had towed guns by the time of the Battle of the Bulge.
As World War II progressed, the balance shifted back and forth between heavier and more powerful AT guns and thicker and heavier tank armor. Tank designers were faced with the challenge of developing tanks with guns powerful enough to defeat enemy armor, yet with armor strong enough to resist the fire from enemy tanks and AT guns. Larger guns produced more recoil, which required a larger and heavier turret. That combined with stronger armor added to the overall weight of the tank, decreasing the tank's mobility and creating a larger target. Most World War II tanks had heavier armor on the front and sides, where the tank was more likely to be attacked.
Tanks can be defeated in differing degrees, with correspondingly different results. In a mobility kill, a tank becomes immobilized because of damage to its treads or drive train. Many mobility kills resulted when a tank hit a mine. An immobilized tank can still fire, but it can no longer maneuver. The advantage from the attacker's standpoint is that the tank becomes more vulnerable to subsequent attack. A firepower kill happens when the tank's main gun system can no longer fire. Although the tank has almost no combat power at that point, it still has the mobility to withdraw from the action, where it can be repaired and placed back into service. A total kill results when the tank is completely destroyed and the crew is killed or severely wounded. In some situations, a trained tank crew may be more difficult to replace than the tank itself.
There are two basic categories of AT projectiles, kinetic energy and chemical energy. A kinetic energy round is a solid-shot projectile that depends on weight and velocity to penetrate and defeat opposing armor. As weight and velocity increase, so does penetrating power. The distance to the target is also a factor. As the round travels farther, its velocity and penetrating power decrease accordingly. The German 88 mm PAK 43 could penetrate 207 mm of armor at a range of 1,640 ft but only 159 mm at a range of 6,562 ft.
The angle of impact also affects a round's penetrating power. At a 30-degree angle of impact, the penetrating power of the PAK 43 at 1,640 ft dropped to 182 mm. Thus, beginning with World War II, most tanks have had sloped armored fronts. The earlier kinetic energy rounds also had a tendency to ricochet off the sloped surfaces. The solution to that problem was a special soft nose cap that allowed the round to stick to the armor surface just long enough for penetration to begin.
Tapering the bore of the gun also could increase the velocity of a kinetic energy round. The squeeze-bore guns fired a round with a plastic driving band that wore away as the round moved forward through the bore. As the bore narrowed, the pressure behind the round increased, which in turn increased muzzle velocity. As the round left the gun's muzzle, the remnants of the driving band fell away. The Germans used this technique on their smaller 42 mm and 75 mm PAK 41 antitank guns, but technical factors limited the effectiveness of the squeeze-bore technique in larger calibers.
Dense and heavy material such as tungsten made the best kinetic-energy rounds. But at 1.4 times the density of steel, a projectile made completely from tungsten would have been too hard and too heavy for the bore of the gun to survive more than a handful of firings. In 1944, the British solved that problem with the introduction of the armor-piercing discarding sabot (APDS) round. A relatively small but heavy main projectile was encased completely in a plastic casing that fell away as soon as the round left the muzzle. This system had the advantage of placing the pressure produced by a large-bore gun behind a smaller projectile. The result was greater velocity and penetrating power. The APDS remains the primary AT round today.
Chemical-energy rounds defeat armor through a blast effect. The effectiveness of the round depends on its size, composition, and physical configuration rather than on its velocity. Chemical energy rounds tend to travel more slowly and have a more arched trajectory than kinetic energy rounds. Thus, their aiming is far more dependent on an accurate estimate of the range to the target.
Chemical-energy projectiles that produce a uniformly distributed blast effect, such as conventional high-explosive (HE) field artillery rounds, were effective against tanks only in the very early days of World War II. But as the war progressed and armor got heavier and stronger, riveted tank hull construction gave way first to welding and then to whole casting. In response, rounds known as hollow-charge or shaped-charge rounds were developed based on the so-called Monroe Effect. In a hollow-charge round, the explosive material is configured in the shape of a recessed cone, with the base of the cone toward the front of the round. The surface of the inverted cone is lined with light retaining metal such as copper. When the round first hits the target, the explosive is detonated from the rear of the round forward. The hollow cone has the effect of focusing the entire force of the blast onto a small spot on the tank's skin exactly opposite the apex of the cone. The result is a very hot and very concentrated jet of gas that punches its way through the tank's armor and sends red-hot fragments into the tank's interior. The tank crew is killed by its own armor. The shaped-charge chemical-energy rounds were designated "high-explosive antitank" (HEAT).
When a HEAT projectile is fired from a conventional gun tube, the stabilizing spin imparted by the bore's rifling tends to degrade the round's penetrating power. That led to the development of fin-stabilized projectiles fired from smooth-bore launchers, such as the bazooka and Panzerfaust. These close-range infantry weapons proved relatively effective. The HEAT warheads did not depend on velocity, so they could be fired from relatively light weapons. HEAT projectiles do depend on warhead weight, however, and in these weapons, that was limited to what an infantryman could carry.
No single system stood out in World War II as the premier tank killer, although certain systems predominated at certain times and in certain theaters. Overall for the war, some 30 percent of British tanks that were knocked out fell victim to antitank guns, 25 percent were knocked out by enemy tanks, 22 percent hit mines, 20 percent fell victim to artillery indirect fire and air attack, and the rest were knocked out by infantry AT weapons. In North Africa, Axis AT guns accounted for 40 percent of the British tanks knocked out, whereas in Italy it was only 16 percent. Throughout the war, German tanks were generally better armed and more powerful than their British and American counterparts. That meant that Allied tanks destroyed far fewer panzers than the other way around.
David T. Zabecki
Bailey, Jonathan B. A. Field Artillery and Firepower. 2d ed. Annapolis, MD: Naval Institute Press, 2003.; Gabel, Christopher R. Seek, Strike, and Destroy: U.S. Army Tank Destroyer Doctrine in World War II. Ft. Leavenworth, KS: Combat Studies Institute, U.S. Army Command and General Staff College, 1986.; Hogg, Ian V. German Artillery of World War Two. Mechanicsburg, PA: Stackpole Books, 1975.; Weeks, John S. Men against Tanks: A History of Antitank Warfare. New York: Mason/Charter, 1975.