Written by Matthew Copes
Throughout the Second World War the development of heavier tanks with thicker armor and more powerful guns was a top priority for most nations.
That said, America didn’t have a true “heavy” until M-26 Pershings began showing up in limited numbers in late 1944.
Instead, the United States focused on churning out nearly 50,000 Sherman medium tanks, though in most respects they matched up poorly against their German counterparts.
Likewise, the Soviet Union produced nearly 60,000 T-34s that ultimately got most of the credit for stemming the Nazi tide on the Eastern Front.
By comparison, Germany produced relatively few tanks, and as the war dragged on manufacturing slowed even further thanks to constant Allied aerial bombardment as well as shortages of fuel, labor and raw materials.
But though the Germans rarely enjoyed numerical superiority, at least in the early going many of their tanks and armored vehicles were head and shoulders above the competition.
In addition, their crews were often more efficient and battle-hardened, but with the introduction of KV series tanks of which more than 5,200 were built, the playing field became more level, and when T-34 production hit its stride the war’s trajectory changed drastically.
Named in honor of Soviet politician and Red Army Defense Commissar Kliment Voroshilov, KV tanks were primarily known for their thick armor that was nearly impervious to the low-velocity guns on early Panzers and Stugs.
In fact between late 1941 and mid-1942, the only weapons in the German arsenal capable of consistently taking out KVs were the vaunted 88s, which at the time were used primarily in the anti aircraft role.
KV’s 76.2 mm guns were exceptionally powerful by early war standards, and in conjunction with their thick armor it was common for a handful of these Soviet behemoths to hold off large concentrations of German infantry and armored vehicles from great distances.
Hence, based on their size and weight they were often referred to as the “Russian Colossus,” and the Germans quickly learned to engage them only when they could be ambushed, outflanked or overwhelmed with superior numbers.
Prior to Operation Barbarossa in late June of 1941, the Soviet Union purportedly had more than 20,000 tanks in service, though many were outdated models from the ‘20s and ‘30s.
Only about 500 KV-1s were in service at the time of the invasion, but by then the new T-34 medium tanks were being produced as well.
However as the war progressed it became evident that producing the two tanks simultaneously didn’t make much sense, because in most respects T-34s were equal or superior to their larger cousins.
T-34s shared the same cannons with many KV variants, but they were lighter, more reliable and more mobile, and they could be manufactured more quickly and inexpensively.
In the years between the First and Second World Wars the Soviets developed an odd behemoth called the T-35 Heavy Tank that had more turrets than most medieval castles.
Considered one of the first true “breakthrough tanks,” their job was to punch gaping holes in enemy defenses with overwhelming force, after which infantry and lighter mechanized units could stream through largely unmolested.
This concept became popular after the horrors of trench warfare in the Great War, and it guided tank development for decades after World War II ended.
Crewed by ten, tipping the scales at nearly 50 tons (45,300 kg), and standing more than 11 feet (3.4 m) tall, T-35s were impressive machines.
That said, they were expensive and time consuming to build, prone to engine and transmission breakdowns, and far less mobile than most tanks of the era.
No surprisingly only about 50 were built, and as such the Soviets were faced with the daunting task of developing an entirely new heavy tank.
Several manufacturers submitted design proposals, nearly all of which featured gobs of armor, large guns, cast steel hulls and wide tracks to minimize ground pressure.
Though some designs initially featured multiple turrets, these were scrapped due to their increased weight, complexity and cost.
KV-1s were one of three single-turret designs ordered into limited production just before the Soviet Union invaded Finland in late November of 1939.
Known as the Winter War, Stalin ordered the invasion based largely on the assumption that the Finns would have no choice but to permit the Nazis to use their country as a staging point from which an all-out attack on the Soviet Union could be launched.
Though the Winter War was a debacle for the Soviets, the KVs generally outperformed the other tanks that’d been pressed into service.
Their heavy armor proved highly resistant to Finnish anti-tank weapons of various calibers, but a number of serious flaws were revealed as well.
The 76.2 mm guns were powerful enough to take out tanks and other armored vehicles from long ranges, but they weren’t up to the task of dealing with the reinforced concrete bunkers that dotted the defensive Mannerheim Line.
Since this severely impeded Soviet progress, a number of requests were made by commanders to fit more powerful guns into KVs.
This led to the development of KV-2s – unaesthetic, topheavy leviathans with massive 152 mm cannons protruding from bulbous high-profile turrets.
But though the new KV-2s looked like tanks, they functioned more as self-propelled artillery pieces and mobile siege guns.
They were so heavily armored that they were often tasked with creeping to within a few dozen meters of hardened enemy targets and delivering one-punch knockout shots, after which infantry and lighter armored vehicles could pass.
On the downside, KV-2s couldn’t keep up with the rest of the forces, and their turrets were so heavy that they could only be traversed on relatively flat ground.
Though production ceased in 1943, KV-1s were the most mass produced of all KVs with nearly 4,000 units being built, while by comparison just more than 200 KV-2s were manufactured.
Each KV-1 weighed about 45 tons (40,800 kg) and was protected by between 25 and 120 mm (1 and 4.7 inches) of armor, the thickest of which was located on the front of their hulls and turrets.
Both KV-1s and 2s were powered by the same 600-horsepower diesels, but while the former were moderately mobile, the latter’s oversized turrets and guns added another 10+ tons (9,700 kg) of weight that made them particularly sluggish.
In addition, KV-2s were plagued by even worse mechanical issues than KV-1s, and many were sent into battle with spare transmissions chained to their rear decks.
KVs in Action
Just days after Operation Barbarossa commenced, nearly 1,000 German and Soviet tanks clashed near the Lithuanian town of Raseiniai.
While larger engagements raged nearby, on June 23rd a column of German tanks encountered a much smaller Soviet armored force – one that may have consisted of just one KV-1.
Accounts vary wildly, but it’s thought that a lone KV-1 withstood days of heavy fire from the 6th Panzer Division near a vital crossroads.
The Soviet tank took multiple hits and received minor damage, but none of the rounds penetrated the armor, and as a result the larger German force’s advance ground to a halt.
To dispatch the pesky defender, the Germans called up an 88 mm gun from a nearby anti-aircraft battalion and positioned it about 800 yards away from the KV.
Before they could score a hit however, the KV’s crew destroyed the gun, and after the sun had gone down the frustrated Germans sent in a small unit of combat engineers to take out the tank with satchel charges.
They only succeeded in disabling the Soviet tank’s tracks, but with their prey finally immobilized and vulnerable, another 88 was pressed into service.
Its crew put two rounds through the KV’s armor in quick succession, but as wary infantry advanced to inspect the wreckage they were met with a barrage of fire from the stricken tanks defensive machine guns.
Somehow the crew had survived two direct hits from one of the war’s most powerful guns, but when grenades were dropped through hatches that’d been blown off, all activity inside ceased.
According to some accounts the Germans buried what was left of the tank crew with full military honors, while others claim that the Soviet tankers escaped the night before under the cover of darkness.
Just months after the engagement in Reseiniaia, nearly two dozen German tanks from the 8th Panzer Division ran headlong into five KV-1s on the outskirts of Leningrad.
Aware of the German advance since the previous day, each KV-1 had been stocked with twice the number of shells that they typically carried.
Outnumbered nearly 5 to 1, Soviet Commander Lieutenant Zinoviy Kolobanov used the local terrain to his advantage by concealing his tanks next to a swamp just a few hundreds from the main thoroughfare leading into town.
As the first German tank lumbered into view Kolobanov ordered the other commanders to hold their fire.
Fearful of alerting the Germans that they were facing a numerically inferior force, Kolobanov planned to engage them with his own tank first and leave the others in reserve.
Then with an armor-piercing round locked into the breach, Kolabanov’s gunner sent the projectile down the tube, and seconds later it punched its way through the lead tank’s armor.
When it burst into flames the Germans thought it’d run over a mine in the road, and when the rest of the column stopped the second tank was destroyed, followed by the last in line, effectively boxing the rest in.
Now the Germans were sure they were under attack from tanks, tank destroyers or artillery, but the Soviets were so well concealed that they couldn’t determine where the fire was coming from.
Some German tanks held their ground and fired wildly, while others attempted to flee and became stuck in the swamp.
The ensuing turkey shoot resulted in Kolobanov’s KV taking out nearly two dozen tanks on its own.
When his ammunition was nearly exhausted, he ordered the others to open fire, and in approximately 30 minutes 20 more German tanks were destroyed.
All told more than 50 German tanks may have been taken out with no KV’s lost, but as impressive as it was, most were thinly armored Panzer IIs armed with anemic 20 and 37 mm guns.
Together, this meant that they had neither the range nor power to punch through the KV’s armor, and their own armor was hopelessly outclassed against the KV’s larger guns.
When the smoke had cleared Kolobanov’s crew counted more than 130 hits on their tank, none of which had penetrated into the crew compartment.
Kolobanov was awarded the Order of Lenin, while his gunner was awarded the Order of the Red Banner.
Kolobanov’s tactics and leadership shone in other armored engagements as well, but he later fell out of favor with Soviet leadership and was imprisoned on charges of fraternizing with the enemy.
After the war and the division of Germany, he escaped to the Allied occupied zone.
Few military engagements in history come close to matching the forces arrayed against one another in the Battle of Kursk between July and August of 1943.
By far the world’s largest tank engagement, the battle included 6,000 armored vehicles, 2 million men and nearly 4,000 aircraft, but though only about 200 KVs saw action, the Soviet victory ultimately turned the tide of the war.
In the end Hitler’s dream of conquering the Soviet Union was dashed, and shortly thereafter the Soviets began the great push that culminated in brutal street fighting and the conquest of the Reichstag building in the capital city of Berlin.
But despite outnumbering and outgunning the Germans, Soviet forces suffered much greater losses at Kursk, though at that stage they were in a much better position to replace the equipment that’d been lost.
Though the data is sketchy, it’s estimated that the Soviets may have lost as many as 800,000 soldiers and 1,500 tanks, compared to 200,000 and 500 for the Germans respectively, though many historians claim that these figures may be significantly understated.
Throughout their relatively short service lives, combat revealed a number of Achilles heels across the KV line.
Due to their weight KV tanks were often unable to cross bridges that medium tanks could, and as a result they were often “no shows” in significant engagements.
Up until Tigers and Panthers were introduced, they were nearly twice as heavy as some of the tanks they faced, but ironically this was almost exclusively due to the two things that made them so effective – their guns and armor.
In addition to suffering from the aforementioned engine, transmission and mobility issues, crews also had poor visibility and ineffective communications equipment compared to their German counterparts.
But though armor protection was excellent, as more potent long-barrelled, high-velocity 50, 75 and 88 mm guns became more common in German tanks, this advantage became less pronounced.
KVs were also susceptible to attack from the air, and their thin top and rear armor could be penetrated by the 20 and 30 mm cannons in ground attack aircraft like Ju-87 Stukkas and Henschel Hs 129s.
KV-1’s 76.2 mm guns also left much to be desired as the war progressed, and by 1943 they were no longer capable of penetrating the frontal armor of newer and heavier German tanks unless fired from dangerously close ranges.
Though these concerns were occasionally voiced, it goes without saying that Stalin didn’t generally respond well to naysayers.
However in response to battle statistics and diplomatic pressure from members of his inner circle, Stalin had no choice but to admit that his beloved KVs were in dire need of some improvement.
Gun and armor upgrades were eventually introduced, but both made the tanks even less mobile and transportable, and in the end the decision was made to cease production and focus on building T-34s in the greatest quantities possible.
Though KV-2s did excel in the bunker-busting role, the fact was that neither they nor the smaller KV-1s were particularly suited to the fluid tactics of the Second World War.
In response to the former KV’s excessive weight, lighter, more thinly armored and more mobile KV-1S were developed.
KV-1Ss had a number of additional improvements including an upgraded commander’s cupola which provided better visibility, and more reliable transmissions that minimized breakdowns.
Though crews appreciated their new tank’s increased speed and reliability, their thinner armor was a constant source of concern.
Some KV-1Ss also got more potent 85 mm cannons that were capable of knocking out the heaviest German tanks at ranges approaching 1,000 meters, but these were short-lived, largely because the hefty guns took up more turret space which caused efficiency to drop.
As the war dragged on heavy and super-heavy tanks began falling out of favor, but though a new series of IS heavy tanks named after Joseph Stalin were introduced in 1944, they were produced in relatively limited numbers.
Featuring more modern designs, low-profile silhouettes and massive 122 mm main guns, IS-1 and 2 tanks would spearhead the Red Army’s push to Berlin.
While the Soviet 122s had lower muzzle velocities than many German guns of smaller caliber, their greater mass often translated into more armor penetration, in some instances out past 2,500 meters.
In addition, when firing high-explosive rounds they were devastatingly effective at knocking down buildings and makeshift fortifications in the Battle of Berlin.
On the downside, their bulky two-piece projectiles limited the number of rounds that could be carried and reduced their rates of fire.
By this time however, experienced German crews and battleworthy tanks were in painfully short supply, and of the IS-1’s, 2s, and T-34s lost, many fell victim not to other tanks, but to mines, artillery, and Panzerfaust anti-tank weapons.