At dawn on 5 July 1943, before the first German tank rolled forward, large formations of Soviet bombers, Shturmoviks and fighters headed for the Luftwaffe airfields around Kharkov and Belgorod. The plan was simple: catch the German air fleet on the ground in the hour Operation Citadel began. It went badly wrong. By evening the Soviet air force, the VVS, had lost 176 aircraft and the Luftwaffe 26, according to the figures used by historians Niklas Zetterling and Anders Frankson.

Kursk is remembered as the great tank battle of the Second World War. Above the steppe, a second battle decided where the panzers could move, which Soviet counter-attacks got through and which burned before they reached the front. It was also a laboratory: new anti-tank weapons appeared on both sides, and the claims made for them have been argued over ever since.

The Kursk air battle is also where the Luftwaffe lost the initiative in the East. It still won individual days, and some of them spectacularly. It could not win the summer.

Two air fleets against three air armies

The Luftwaffe of 1943 was already stretched thin. Fighter units had been pulled back to defend Germany against the Allied bomber offensive, and the Mediterranean swallowed more. By the end of June only 38.7 per cent of the Luftwaffe's aircraft remained in the East, and most of them were committed to Citadel.

In the north, Luftflotte 6 under Robert Ritter von Greim supported Walter Model's 9th Army. In the south, VIII Fliegerkorps of Luftflotte 4 supported the 4th Panzer Army and Army Detachment Kempf. Together they mustered about 1,800 aircraft. Fuel was the binding constraint: the Luftwaffe cut back its flying in the last week of June just to build stocks, and still could not sustain an all-out effort for more than a few days.

Facing them were the 16th Air Army with Rokossovsky's Central Front in the north and the 2nd Air Army with Vatutin's Voronezh Front in the south, soon reinforced by the 17th Air Army. Writing for HistoryNet, Dan Zamansky counts 3,028 aircraft in these three air armies, 1,414 of them fighters. The new Yak-9 et La-5 had closed much of the quality gap with the Bf 109G et Fw 190, and behind the front stood stockpiles and replacement aircraft that the Germans simply did not have.

The Armchair Historian's animated history of Kursk told from the air, from the opening strikes to the Soviet counter-offensives.

5 July: the strike that hit nothing

The Soviet commanders knew the date of the attack almost to the hour, and the obvious move was to hit the German airfields first. Early on 5 July the VVS sent a large raid against the bases around Kharkov and Belgorod. German fighters of JG 3 and JG 52 scrambled at the last minute, and the attackers ran into them. The raid destroyed little on the ground and cost the attackers heavily.

The story is often told as a triumph of German radar. The Freya stations at Belgorod and Kharkov did detect formations heading for Belgorod, but more recent research concludes that they were not responsible for the failure of the whole operation. Timing, poor coordination and fighters in the right place mattered as much. The 16th Air Army in the north got off more lightly than the 2nd Air Army in the south.

The day as a whole was brutal. German fighter pilots filed several hundred victory claims; Zamansky gives 367, while 166 Soviet pilots were recorded dead or missing. Some histories call 5 July the costliest single day of air combat ever fought, measured in aircraft shot down. Over the southern face the Luftwaffe held air superiority until about 10 to 11 July. In the north the sky was contested until the VVS took control on 7 July and kept it.

PTAB: the 2.5-kilogram tank killer

Kursk also saw the debut of a weapon that changed what an Il-2 Shturmovik could do to armour. The PTAB was a small shaped-charge bomblet in the 2.5-kilogram class, carrying roughly 0.6 kg of explosive. Its jet could punch through about 60 mm of armour, and the roof of a tank is far thinner than its front.

The trick was quantity. An Il-2 could carry 192 PTABs in four cassettes of 48 and release them in a stream that carpeted a strip of road or a tank harbour. According to Soviet records cited by the Russian historian Oleg Rastrenin, more than 1.17 million had been dropped by the end of 1943. The Il-2 itself became one of the most-produced military aircraft in history, with 36,183 built.

According to Russian archival research published by Tank Archives, the first combat use came on 5 July 1943, by assault air corps of the 17th Air Army, and Kursk saw the weapon's first large-scale use. Soviet pilots reported dozens of tanks destroyed in the first two days. The Germans adapted fast: they spread their vehicles out on the march and in assembly areas, and the bomblets' effect fell accordingly.

Claims versus panzers

This is where the arithmetic turns treacherous. Soviet sources claimed that Il-2s destroyed 70 tanks of the 9th Panzer Division in just 20 minutes, and 270 tanks of the 3rd Panzer Division in two hours. On 1 July the 3rd Panzer Division's 6th Panzer Regiment had just 90 tanks, and the division recorded no extraordinary losses to air attack in that period.

Studies of German records conclude that only a small share of German tank write-offs at Kursk was caused by aircraft of any kind; anti-tank guns and armoured vehicles did most of the killing. That does not make the Shturmoviks irrelevant. They hit trucks, guns, infantry and supply columns, and they forced the panzers to spread out. They also paid a terrible price: in 1943 one Il-2 was lost for every 26 sorties.

Military Aviation History asks the question at the heart of the battle: who actually won the air war over Kursk?

Kanonenvogel and Hs 129: the German tank-busters

The Luftwaffe brought its own experiments. The Ju 87G carried two 3.7 cm BK 3,7 cannon in pods under its wings, each with only 12 rounds. Crews called it the Kanonenvogel, the cannon bird. At Kursk it flew as a small experimental contingent, led by Hans-Ulrich Rudel of StG 2, and the battle was its combat debut.

Rudel's own tally is the stuff of legend and of doubt. He is credited with 12 Soviet tanks in a single day during the battle, though accounts disagree on whether that was 5 July or 12 July. His wartime total of 519 claimed tanks is not confirmed by any primary source.

The armoured Henschel Hs 129 carried a 30 mm MK 103 cannon under its fuselage, and all four of its squadrons operated in the south. Their big day came on 8 July, when German air reconnaissance spotted the Soviet 2nd Guards Tank Corps moving through woods near Gostishchevo against the 167th Infantry Division on the flank of the II SS Panzer Corps. The Hs 129s caught it in the open, and German accounts credit them with at least 50 tanks. The episode is often called the first time an attacking tank force was stopped by aircraft alone, a claim that rests largely on German reporting.

On 12 July, the day of Prokhorovka, VIII Fliegerkorps concentrated over the battlefield while the Soviet air armies spread themselves across other sectors. Schlachtgeschwader 1, which flew the Hs 129, and the tank-hunting squadron of JG 51 flew 248 attack missions, virtually all in support of the II SS Panzer Corps.

Counting the cost: whose numbers?

Air losses at Kursk are a minefield, and the Swedish historian Christer Bergström has done more than anyone to clear it. Working from Soviet archives, he puts VVS losses during the German offensive at 677 aircraft on the northern flank and 439 on the southern flank. The official Soviet figure for the whole battle is 1,626. The German historian Karl-Heinz Frieser calls that figure completely unbelievable and cites Boris Sokolov's minimum of 3,300, while German pilots claimed 4,209.

German losses look modest by comparison, but they were not cheap. Frieser counts 524 Luftwaffe aircraft for the whole battle: 159 during Citadel, 218 against Operation Kutuzov and 147 against Operation Rumyantsev. Bergström, reading the Luftwaffe quartermaster's reports, finds 681 aircraft lost or damaged between 5 and 31 July, 420 of them written off.

The gap between claims and losses runs through every side of this story. Fighter pilots over-claimed, Shturmovik crews over-claimed, tank-busters over-claimed. The safest reading is a range, attributed, and a healthy suspicion of any single number that sounds too round.

Winning days, losing the summer

On 10 July the Allies landed in Sicily. Two days later, with the Kursk air battle at its height, the Red Army launched Operation Kutuzov against the Orel salient behind Model's 9th Army, and that evening Hitler summoned his two army group commanders, Kluge and Manstein, to tell them Citadel had to stop. Luftwaffe units were shuttled north to plug the gaps, and the German air effort in the south thinned out just as the Soviets attacked there too.

The underlying problem was depth. The Luftwaffe had no reserve of aircraft to replace what it lost, and its pilots flew themselves into exhaustion. The VVS absorbed losses that would have broken the Luftwaffe, replaced them and came back stronger. By late 1943 only about a quarter of the Luftwaffe's day fighters were on the Eastern Front; the rest were defending the Reich against American and British bombers.

Kursk was the last major German strategic offensive in the East. After it the Kursk air battle stopped being a contest of equals, and the sky over the Eastern Front belonged, increasingly, to the Il-2 and its escorts. The Luftwaffe had won the first morning. The Red Army air force won the war of attrition that followed.

Real Time History explains why Germany lost the Battle of Kursk, including the role of reserves, intelligence and air power.

Sources: Wikipedia (Battle of Kursk, Operation Citadel, Battle of Prokhorovka, Ilyushin Il-2, PTAB, Hans-Ulrich Rudel, Henschel Hs 129), Christer Bergström (Kursk: The Air Battle, July 1943), Karl-Heinz Frieser, Niklas Zetterling and Anders Frankson, Dan Zamansky (HistoryNet), Air & Space/Smithsonian, Tank Archives (Peter Samsonov), WarHistory.org