The Battle of Kursk (July 4, 1943 - August 23, 1943) was after Stalingrad, the most important battle during the Second World War.
Following their disastrous defeat at Stalingrad (1942-43), the German forces launched its spring offensive in the East on July 4, known as Operation Citadel, in order to regain the initiative in the Russian front. The Battle itself involved around 6000 tanks, 4000 aircraft and over 2 million soldiers fighting on the ground.
One of the most important things in WW2 was the intelligence and knowing what the enemy was planning and, Kursk. was a great example. The USSR had good intelligence about the German plans and established deep defensive positions and gathered large forces in reserve.
To prepare for the defense, 300,000 Red Army soldiers and civilians built a series of defenses including tank traps, mine fields, and various defensive positions. Militarily, Zhukov wielded a strength consisted of 1,300,000 men, 3,600 tanks, 20,000 pieces of artillery, and 2,400 aircraft. On the other side, the Germans were about to attack with over 800,000 men (including three Waffen SS divisions), 2,700 tanks, and 1,800 aircraft.
The battle started on July 4, 1943, after sappers of the Großdeutschland Division bravely and efficiently cleared a path through the mine fields the previous night, German Stuka fighters led the attack targeting the lightly armored tops of Soviet tanks, followed by an artillery barrage then by the infantry and armor. The 2nd SS Panzer Corps, 3rd Panzer Corps, and the 11th Panzer Division stormed Soviet positions, making advances through the rest of the day, but the Soviets resisted fiercely and slowed the German advances. Main reasons for the slow German advance were often attributed to the defensive structures, especially mine fields, that the Soviets painstakingly set up. Also, Walther Model of the German Ninth Army was employing a rather conservative tactic with his tanks, withholding some in reserve instead of following the usual German tactic that poured all armor strength into battle immediately. Around midnight Zhukov, armed with good intelligence on German movement, ordered a bombardment by artillery pieces, mortars, and Katyusha rocket launchers accurately on German forces.
On the next day, Paul Hausser's 2nd SS Panzer Corp advanced under a newly devised tactic Panzerkiel, where Tiger tanks opened the way for other tanks, prying through enemy defensive lines. By the second day of the Kursk offensive, German troops had penetrated 20 miles into Soviet territory, at a high cost on both sides. At Prokhorovka Hausser's flanks were supposed to be protected by the 3rd Panzer Corps, which was unexpectedly stalled by the 7th Guards Army. To take advantage of the situation, the entire 5th Guards Tank Army was deployed to strike at the 2nd SS Panzer Corps on 12 Jul, which was to become the largest tank battle in history. Armor on both sides engaged in close-range combat, while air forces took their shots at the tanks on the ground amidst the fierce dogfights in the air. Armor-piercing anti-tank guns also made their share of damage during the battle. As tanks on both sides burned and sent thick smoke into the sky, aircraft could no longer tell friend from foe, and slowly disengaged themselves from ground targets in fear of striking friendly units. At the end of the day when the battle subsided, the Germans had lost 60 tanks and Soviets 822.
As casualties mounted high for both sides, Hitler made a surprising announcement to withdraw part of the German forces to reinforce Italy, a response to the successful western Allies' landing in Sicily. After the German strength weakened after the withdrawl, Soviet forces continued on to liberate Oryol, Belgorod, and Kharkov after the Battle of Kursk.
Although the Soviet forces suffered heavier casualties at Kursk than the Germans, the engagement was a success for the Soviets in that they stopped a planned German offensive. Historians attributed a tactical victory to the Soviets at Kursk for that the German forces were depleted and demoralized at the end of the battle without support of reserve forces. Manstein made the recommendation to Hitler that a final reinforcement at Kursk could have turned the tides of the battle and destroyed the Soviet troops present in the area mending their recently received wounds, but Hitler had already made up his mind to shift his focus to Italy. At the end of the fighting in Kursk, the German forces had suffered 200,000 casualties and lost 500 tanks, while Soviet losses amounted to 860,000 casualties and 1,500 tanks. Although the Soviet losses in tanks were greater than that of the Germans, at this time the Kirov tank factory along with other factories on the east side of the Ural mountains were just reaching their peak production capability while the German factories were becoming stressed. In fact, German armor would never regain its numerical superiority over their Soviet counterparts again.