'Flax' was the Allied air offensive to disrupt the Axis air bridge between Tunisia and Sicily, very large numbers of German and Italian transport aircraft being shot down as they tried to evacuate as many Axis troops as possible in the face of imminent Axis defeat in North Africa (5/22 April 1943).

As such, 'Flax' was the aerial counterpart of the naval 'Retribution'.

After 'Torch', the Allied forces had moved to the east through French North Africa, and quickly overrun French Morocco and Algeria before moving into western Tunisia. The strategic threat now facing the Axis powers was all too evident, for while Lieutenant General K. A. N. Anderson’s Allied 1^st Army was advancing from the west, General Sir Bernard Montgomery’s British 8^th Army was advancing from the east after its victory in the 2^nd Battle of El Alamein. This threatened to trap, and then to encompass the destruction, of all the Axis forces still in North Africa, namely Generalfeldmarschall Erwin Rommel’s (from 9 March Generaloberst Hans-Jürgen von Arnim’s) Heeresgruppe 'Afrika'.

In response both to the crisis and to the poor state of Axis forces, which had suffered a series of major reverses, reinforcements were sent by sea and air, and helped to deny the Allies their chance to secure an early victory in Tunisia, especially as the wholly indifferent nature of the rail and road networks in Algeria faced the Allied 1^st Army with acute logistical difficulties in their eastward advance, and thus afforded the Axis forces the opportunity to prolong their defence of Tunisia, which was the last part of North Africa left to Germany and Italy. Even so, the growing strength and capabilities of the Allied forces steadily compressed the Axis forces into the north-eastern tip of Tunisia.

During this time the British air and sea interdiction campaign from Malta was having a major effect on the Axis forces' capacity to wage an effective land campaign against the Allies, for the Axis forces were running acutely short of the munitions and fuel necessary for sustained operations. By April 1943 the Allied armies had pushed the supply-starved Axis forces to the north-east tip of Tunisia, near the capital city of Tunis.

Despite the desperate situation, the Oberkommando der Wehrmacht and Comando Supremo continued their efforts to deliver significant numbers of men and tonnages of supplies. The British naval and air forces operating from Malta were still taking a very heavy toll of the Axis ships attempting to deliver men and matériel, but supplies were still reaching the Axis forces by aircraft which, from a time early in April, also started to evacuate significant numbers of Germans and Italians in aircraft returning to Sicily.

The Allies had virtually total air superiority by day, despite the fact that in the first weeks of 1943 the Axis had a numerical advantage with about 690 aircraft to the Allies' 480, but at night the Axis transport aircraft were able to fly into and out of Tunisia with little chance of interception.

To prevent the chance of an extended Axis resistance, and now knowing of the Axis supply timetables from 'Ultra' intelligence, the Allies organised and launched an air offensive to destroy the Axis air bridge. This 'Flax’0 offensive was scheduled to begin during the last week of March 1943, but adverse weather and the need to gather additional intelligence meant that the operation in fact began only on 5 April and lasted to 27 April. The Axis situation in the air was already becoming worse on an incremental basis, and Axis supply ships had suffered heavy losses between Cape Bon and Sicily: two-thirds of the shipping losses were attributable to the depredations of Allied aircraft.

In response Generalleutnant Theo Osterkamp was appointed as the Jagdfliegerführer 'Sizilien', and on 7 April he was allocated 148 fighters with which to reduce the Allies' success in attacks on Axis shipping.

At much the same time the Luftwaffe reorganised its forces in Tunisia: on 12 March General Hans Seidemann had been appointed to head the Fliegerkorps 'Tunis', which had three subordinate commands in the form of the Fliegerführer 'Tunis', Fliegerführer 'Mitte' and Fliegerführer 'Gabès' groups for air operations over northern, central and southern Tunisia respectively. Seidemann had the equivalent of 12 Gruppen with about 300 fighters until a time in the middle of April.

The air bridge between Sicily and Tunisia was the responsibility of Generalmajor Ulrich Buchholz, Geschwaderkommodore of the KG zbV 3, who had become the Lufttransportführer II, Mittelmeer on 15 January with his forces organised under the KG zbV Nord based at Naples and the KG zbV Süd based at Trapani in Sicily: the former had to undertake one longer-range mission per day from the Italian mainland, and the latter two shorter-range missions per day from its Sicilian bases, with formations of between 80 and 120 aircraft. The missions were flown at an altitude of less than 165 ft (50 m), and were timed so that the aircraft reached Tunisia at about 12.00 to coincide with the Allies' time of minimum activity.

Units flying the Junkers Ju 52/3m three-engined transport delivered about 88.5 tons per day, while those operating the much larger but considerably less numerous Messerschmitt Me 323 six-engined transport delivered about 29.5 tons. In Tunisia the Axis forces made use of Indian prisoners of war to assist the unloading of supplies.

The tactical method that became standard involved the use of fighters to escort the transports at the rate of about one fighter to every four transports. The outbound transports flying from the area of Naples were met by their escort near Trapani, and on the inbound journey were also escorted from about the same point.

The number of transport aircraft rose to 185 by 10 March, a fact made possible by the end of the German aerial supply effort associated with the Battle of Stalingrad and the support of the Kuban beach-head, and by the first days of April the number of available transport aircraft had therefore increased to 425.

The task of establishing 'Flax' as the Allied scheme to sever the Axis air bridge fell to Major General James H. Doolittle, commanding the North-West African Strategic Air Force. The Allied plan was based on the concept of making interceptions over the narrow stretch of water separating Sicily and Tunisia, though some Allied units were also tasked with major offensive operations against Axis airfields in Tunisia. There were also bombing attacks on the crowded staging fields in Sicily, and continued anti-shipping sweeps. The flight time across the Strait of Sicily was so short that the Allies could plan their interceptions only on the basis of precise intelligence. The Germans appreciated the fact, but remained unaware that their communications had been compromised and were being read by Allied intelligence. This fact helps to explain why the Germans adhered to the notion of launching daylight missions.

The combination of the German switch to night missions and poor weather persuaded the Allies to delay the start of 'Flax' until the Germans had reached the maximum number of aircraft they could muster, and this allowed the Allies to make truly decisive blows against the air bridge in the shortest possible time and in the intelligence-led assurance that the Germans were launching a major mission.

'Flax' included co-ordinated attacks on Axis airfields by US heavy bomber groups with the Boeing B-17 Flying Fortress four-engined heavy bomber to tie down Axis fighter groups. Medium bomber groups flew sweeps with North American B-25 Mitchell twin-engined attack bombers over the Gulf of Tunis, where they were joined by Lockheed P-38 Lightning twin-engined heavy fighters, which were also detailed to sweep the area; the logic of this aspect of 'Flax' was that the presence of the B-25 bombers would allow the P-38 fighters to operate in the area without raising Axis suspicions, for it would seem that the fighters were there to escort the bombers, whereas their real task was to intercept and shoot down Axis transport aircraft. Supermarine Spitfire fighter units swept the strait farther to the north, catching any Axis aircraft which evaded the P-38 fighters. More B-25 and B-17 units were detailed to attack Sicilian airfields in order to catch transport aircraft on the ground.

Major General Lewis H. Brereton’s US 9^th Air Force was instructed to send its Consolidated B-24 Liberator heavy bomber groups against airfields in and around Naples.

On 2 April Air Marshal Sir Arthur Tedder and Lieutenant General Carl A. Spaatz, commanding the Mediterranean Air Command and North-West African Air Forces respectively, decided to wait for the next suitable window to launch the offensive.

'Flax' then started at 06.30 on 5 April as 26 P-38 fighters of Colonel Ralph S. Garman’s US 1^st Fighter Group conducted a sweep over the Strait of Sicily. Meanwhile 18 B-25 aircraft of Colonel Robert D. Knapp’s 321^st Bomb Group, escorted by 32 P-38 fighters of Lieutenant Colonel William E. Covington’s 82^nd Fighter Group, set out on a maritime interdiction operation. Six of the P-38 fighters returned to base for unrecorded reasons, while the bombers claimed two ferries damaged and a destroyer sunk for the loss of one of their own number. The 1^st Fighter Group arrived over Cape Bon at 08.00 and reported contact with several formations of different types, estimating 50 to 70 Ju 52/3m, 20 Messerschmitt Bf 109 and four Focke-Wulf Fw 190 single-engined fighters, six Junkers Ju 87 single-engined dive-bombers and one Focke-Wulf Fw 189 twin-engined tactical reconnaissance aircraft. In fact the German formation had only 31 Ju 52/3m, 10 Bf 109, six to seven Bf 110, four Ju 87 and one Fw 190 aircraft. A large air battle developed, and in this the 82^nd Fighter Group intervened. The 1^st Fighter Group claimed 11 Ju 52/3m, two Ju 87, two Bf 109 and one Fw 189 aircraft shot down for the loss of two P-38 fighters. The 82^nd Fighter Group claimed seven Ju 52/3m, three Ju 87, three Bf 109, one Bf 110 and one Me 210 twin-engined heavy fighter shot down for the loss of four P-38 fighters.

The real German losses are uncertain, and a significant amount of over-claiming was done, and the German losses actually amounted to 13 or 14 Ju 52/3m transports and about three fighters, although another source claims the loss of 13 Ju 52/3m and two Bf 109 aircraft, the latter of the 5./Jagdgeschwader 27. Later, 18 B-17 bombers of Colonel Stanley J. Donovan’s 97^th Bomb Group bombed the Axis airfield at El Aouina, destroying two Me 323, two Ju 52/3m and five Italian transport aircraft. A second mission was flown to Sid Ahmed. Both raids were flown with Spitfire escorts. Only a few German fighters intercepted, and achieved no success, while the bombers claimed one German fighter destroyed.

One hour later, 35 B-25 bombers of Colonel Anthony G. Hunter’s 310^th Bomb Group and 18 P-38 fighters of the 82^nd Fighter Group raided Axis airfields near Borizzo in Sicily. The Allied aircrew counted some 80 to 90 Axis aircraft, poorly camouflaged and vulnerable, and achieved good results with fragmentation bombs. The Allied attackers were intercepted by 15 Bf 109 fighters, losing two B-25 bombers. The bombers and fighters claimed three and two Bf 109 fighter respectively.

Lieutenant Colonel Samuel J. Gormly’s 301^st Bomb Group attacked Milo airfield, claiming 52 aircraft destroyed, but the real Axis losses were 13 German and eight Italian destroyed, together with 11 German and 30 Italian aircraft damaged. Some 72 B-17 bombers of Colonel Fay L. Upthegrove’s 99^th Bomb Group attacked the airfield at Bocca di Falco, where their crews claimed to have seen 100 to 150 aircraft. The raid destroyed only four Axis aircraft and damaged several others. Spitfires claimed two Bf 109 fighters for two losses. Two sweeps by P-38 groups found nothing further. The NASAF claimed 201 Axis aircraft destroyed, including 40 in the air. German sources list the loss of only 14 Ju 52/3m transports in the air and 11 Ju 52/3m and Me 323 aircraft on the ground, as well as 67 damaged.

'Flax' merged into the preparatory phase of 'Husky' (i) and continued on a smaller scale with the emphasis now placed on fighter operations. On 10 April some 75 P-38 fighters of the 1^st Fighter Group intercepted 20 Savoia-Marchetti SM.82 three-engined transport aircraft and about six Macchi C.200 single-engined fighters, and in the ensuing battle 10 transport aircraft and two fighters were shot down. Later that morning, 27 P-38 fighters of Covington’s 82^nd Fighter Group were escorting 18 B-25 bombers of Hunter’s 310^th Bomb Group over Cape Bon when they spotted 30 Ju 52/3m, two Bf 110 (in fact likely to have been Me 210), two Ju 87 and just three Junkers Ju 88 twin-engined aircraft. At first 11 P-38 fighters stayed with the B-25 bombers, but then the bombers joined in, flying past and their gunners firing on the transports. The Germans scrambled about 15 Bf 109 fighters from Tunisia, and these shot down one P-38 and damaged three more. One P-38 pilot was killed when he flew into a Bf 110 and some B-25 bombers were damaged. The Americans claimed 25 victories, but the German record confirms the loss of 10 Ju 52/3m, one Ju 88, one Bf 109 and one Bf 110. Some of the downed Ju 52/3m transports managed to ditch, and their crews survived.

A Supermarine Spitfire single-engined fighter patrol later shot down four more Ju 52/3m transports. British and US units also downed an Fw 190 of Major Wolfgang Schenk’s Schlachtgeschwader 2 on a ferry flight, and another from Major Arved Crüger’s Schnellkampfgeschwader 210. A Henschel Hs 129 twin-engined anti-tank aeroplane of the SG 2 was also shot down, as too was a Ju 88 of the III/Kampfgeschwader 77.

On 11 April the 82^nd Fighter Group encountered 20 Ju 52/3m, four Ju 88, four Bf 110 and seven Bf 109 aircraft. The Americans claimed all the Ju 52/3m transports and seven of the escorts. Actual German losses and the Americans' losses are unclear. In the afternoon 20 of the 82^nd Fighter Group ran into 30 unescorted Ju 52/3m transports. These latter fought back, losing only five and shooting down one P-38, whose pilot was killed. The day’s total amounted to 17 Ju 52/3m, one SM.82 and two Bf 110 aircraft destroyed.

The RAF had also been involved in the day’s activities. No. 152 Squadron sent 34 Spitfire fighters to intercept a dozen Ju 52/3m transports escorted by a few Bf 109 fighters, and shot down three Ju 52/3m transports for the loss of two Spitfire fighters. This had therefore been a bad day for the Luftwaffe, which had lost 18 Ju 52/3m transports, four of them from the III/KG zbV 1. Raids by Vickers Wellington twin-engined medium bombers continued during the night, and Ju 88 night-fighters of Oberleutnant Karl Hülshoff’s Nachtjagdgeschwader 2 shot down two of them.

On 13 April B-17 bombers of the 97^th and 301^st Bomb Groups attacked the airfields at Castelvetrano and Trapani on Sicily. The Italians lost 11 SM.82 transports and had another 16 damaged. At Trapani the Germans lost eight aircraft and 40 damaged by despite the efforts of the fighters of Oberstleutnant Eduard Neumann’s JG 27. Battles over the airfields in the afternoon were inconclusive, costing the Axis one Ju 88 of the II/KG 26 and the RAF one Spitfire of No. 232 Squadron. During the following night air raids killed four fighter pilots of Major W. Beyling’s I/JG 53, and two Ju 88 machines of Hauptmann Sewing’s II/NJG 2 and Hauptmann Anton Stadler’s III/KG 76 were lost.

On 12 April, Air Vice Marshal H. Broadhurst’s Desert Air Force assumed responsibility for most 'Flax' operations. The considerable ranges in these operations stretched the Curtiss Kittyhawk and Spitfire fighters to the limit, and the British spread their forces more thinly than the Americans to maintain continuous coverage. On 16 April, 13 Spitfire fighters encountered a large formation of Axis aircraft, and shot down seven SM.82 transport aircraft and one Bf 109 fighter for the loss of two of their own number. This near-disaster persuaded British commanders to abandon small-scale operations, and from this time onward the British fighter missions consisted of three squadrons of Kittyhawk general-purpose fighters covered by one squadron of Spitfire air combat fighters.

Later on 16 April a small-scale German counterattack involved eight Fw 190 fighter-bombers of Major Günther Tonne’s SKG 10 escorted by 16 Bf 109 fighters of Neumann’s JG 27 on an attack on airfields near Souk el Khemis, where they destroyed six Douglas A-20 Havoc bombers. On the following day Bf 110 fighters of Hauptmann Ralph von Rettberg’s II/Zerstörergeschwader 26 were shot down by Curtiss Kittyhawk single-engined fighters of No. 260 Squadron. Donovan’s 97^th Bomb Group dispatched seven B-17 bombers covered by 40 P-38 fighters to bomb the airfields round Palermo on the northern coast of Sicily. A large air battle developed as 30 Bf 110 and Bf 109 fighters of the ZG 26 and JG 27 intercepted. The Bf 110 heavy fighters attacked the bombers, while the Bf 109 fighters tackled the escort. The Germans claimed five bombers and one fighter for one Bf 109, but the actual Allied losses are unknown.

The patrols failed to intercept any Axis transport formations during the afternoon of 18 April. Late in the afternoon, Colonel Arthur G. Salisbury’s 57^th Fighter Group of the 9^th AAF sent out all of its squadrons, together with the 314^th Squadron of Colonel William K. McNown’s 324^th Fighter Group. The group had already flown unproductive sorties in the afternoon, and the current effort involved 47 P-40 fighters, which arrived in the sweep area at an altitude of about 4,000 ft (1220 m) with 12 Spitfire fighters of No. 92 Squadron flying high cover at 15,000 ft (4575 m). A formation thought to comprise 30 Ju 52/3m transports then appeared at an altitude of only 1,000 ft (305 m), flying to the north-east on a return flight. The actual Axis numbers were 65 Ju 52/3m, 16 fighter and five Bf 110 aircraft. As the Allied fighters attacked, the desperate passengers in the transport aircraft fired machine guns out of the Ju 52/3m machines' windows. In the air battle that followed, six P-40 and one Spitfire fighters were shot down. The Americans claimed 146 victories, which was later reduced to 58 or 59 Ju 52/3m transports, 14 Macchi C.202 and Bf 109 fighters, and two to four Bf 110 heavy fighters. The actual German losses were 24 Ju 52/3m transport aircrafts and 10 fighters (nine Bf 109 and one Bf 110 machines), though it is also possible that some Italian fighters were also shot down. Along with the 24 Ju 52/3m transports destroyed, another 35 were damaged and managed to crash-land all along the Sicilian coast. The battle became known as the 'Palm Sunday Massacre'.

On the following day the South African Air Force’s No. 7 Wing, including Nos 2 and 54 Squadrons, shot down 16 SM.82 transports, and the ease with which these caught fire led the Allied pilots to believe they were carrying fuel as their cargoes. Another source gives Axis losses as 10 aircraft destroyed and four crash-landed. On 22 April No. 7 Wing despatched 36 Kittyhawk fighters, and these intercepted a well-escorted Axis formation. The South Africans claimed 12 Ju 52/3m and two SM.79 transports, one Ju 87 towing a glider, one Reggiane Re.2001 single-engined fighter and two Bf 109 fighters, and one Ju 88 bomber for the loss of five Spitfire and three P-40 fighters. The known Axis losses were 12 SM.79 transports and one C.202 fighter. Spitfire fighters from Malta downed another two transports. A daylight flight later cost the Axis 16 or 17 Me 323 transport aircraft, one C.202 and three German fighters, and one Re.2001 fighter when the Axis formation was intercepted by 36 Australian, British and South African Kittyhawk fighters covered by South African, British and Polish Spitfire units. Four Kittyhawk machines were lost and one Spitfire had to force land.

At this time Reichsmarschall Hermann Göring ordered that no more transport flights to be made, but Generalfeldmarschall Albert Kesselring, the Oberbefehlshaber 'Süd', objected and Göring changed his mind. This time the Axis effort was to be made via airfields on Sardinia, but no more than 60 to 70 flights per night were permitted by comparison with the figure of 250 per day before the start of 'Flax'. The transport aircraft also had to run the gauntlet of radar-equipped Bristol Beaufighter night-fighters, but these rarely achieved successful interceptions. One last effort was made by 70 Consolidated B-24 Liberator four-engined heavy bombers, which attacked airfields around Bari in Italy. Some 54 German aircraft were destroyed and 13 damaged, while the US units involved claimed 50.

'Flax' thus had a considerable effect in strangling the Axis supply effort directed toward Tunisia. The supplies reaching the Axis lodgement in Tunisia steadily dwindled, and the ground and units left in the theatre gradually ran out of fuel, ammunition and other supplies. Having lost most of its air bases, the Luftwaffe also evacuated most of its units. By a time early in May 1943 only the Italian fighter units, and Major Heinz Bär’s I/JG 77, remained as the Axis held on to a narrow strip of the North African coast near the city of Tunis. Allied air superiority was so overwhelming that Luftwaffe personnel climbed into fighter fuselages, or squeezed into the cockpits of Bf 109 fighters alongside their pilots, in their efforts to escape, and indeed most ground crew and pilots attempted to escape this way. Flying large numbers of personnel in a manner as haphazard as this was very dangerous: 16 personnel were killed in the crash of an overladen aeroplane on 29/30 April.

The last Axis transport missions were flown on 4 May, when 117 tons of fuel and ammunition were delivered. Some supply drops were attempted by the II/KG 1, but the signals, transport and administrative staff, as well as Flak personnel, were captured when the campaign ended on 13 May.