The Invasion of Poland

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The PZL.23 Karaś was a Polish light bomber and reconnaissance aircraft designed in the mid-1930s by PZL in Warsaw. It was the primary Polish reconnaissance bomber in use during the Invasion of Poland.



Germany invaded Poland on the morning of 1 September 1939, opening an unbroken period of nearly six years during which the skies of Europe were never quiet. The operation was carefully planned in advance. The Polish Air Force was to be eliminated on the ground by a series of attacks on its airfields, leaving the way clear for the Luftwaffe attack and bomber units to support the ground troops.

It did not work out quite that way. The preceding period of international tension allowed the Poles to disperse their front-line aircraft to temporary strips. Then, in the event, early morning fog disrupted the German plan completely. The airfield assault, when it finally came, fell only upon obsolete and unserviceable combat aircraft and trainers. However, even with this initial setback, the odds were heavily in favour of the Luftwaffe. Not only did they have a sizeable numerical advantage: their aircraft were qualitatively far superior to those of the Poles, while their fighter tactics and training were, thanks to the Spanish experience, ahead of those of any other nation in the world.

The Polish Air Force had been reorganised shortly before the war. On 1 September 1939 the fighter force consisted of a mere 161 aircraft, of which 30 were the obsolete PZL P.7, defending a frontage of approximately 350 miles. To make matters worse, centralised control was lacking. A relatively strong Pursuit Brigade of four squadrons and 45 fighters was based on Warsaw, plus a single understrength squadron far to the south at Krakow with ten obsolete fighters. The remainder were scattered around the various Polish army regions for air defence and bomber escort duties.

This mere handful of fighters, obsolete by the standards of the day, operating from makeshift airfields and using tactics which had remained unchanged since 1917, faced the might of the Luftwaffe. It was backed by a primitive early warning system based on ground observers linked by a rather fragile communications network. Once the shooting started, all semblance of centralised control was lost. Ranged against them were Luftflotten 1 and 4—about 1,500 aircraft in all. The sharp end consisted of 648 level bombers, 219 dive bombers, 30 attack (Schlacht) aircraft and 217 single- and twin-engine fighters. To the small and scattered Polish fighter arm, the odds were overwhelming.

The destruction of German records at the end of the war makes it difficult to establish exactly which fighter units took part in the Polish campaign. However, those known to have participated are detailed in Table 2.

Qualitatively, the disparity between the Polish fighters and those of the Luftwaffe was great. Both the P.7 and P. 11 were monoplanes, with high-set gull wings, fixed landing gear and open cockpits. The P.7 first flew in October 1930, and, powered by a Skoda-built Bristol Jupiter radial engine, could just about exceed 200mph in level flight at 10,000ft. Its rate of climb was 2,047ft/min and wing loading just under 171b/sq ft. Its armament was minimal—two 7.92mm Vickers E machine guns. The P. 11 was basically a heavily modified P.7 adapted to take the much more powerful Bristol Mercury radial. The first prototype flew in August 1931 and the major variant in Polish service, the P.11c, could make 242mph at 18,045ft. Weight had inevitably increased, with wing loading rising to 20.51b/sq ft. The initial climb rate was 20 per cent better at 2,440ft/min, and armament consisted of two KM Wz.33 7.7mm machine guns. It was planned to fit a further pair of machine guns in the wings, but at the outbreak of war only about one third of all P.11s had been so adapted. Radio was another shortcoming: provision for its installation had been made, but it was not fitted to many aircraft.

The early 1930s were a watershed in aircraft design and engineering, and the few years between the advent of the Polish fighters and their German adversaries resulted in a tremendous difference in performance and capabilities. The Messerschmitt Bf 109 variants used against Poland were the C, D and E models. The Bf 109D-1 was powered by the Daimler-Benz DB 600 liquid-cooled engine rated at 960hp, which gave the aircraft a maximum speed of 323mph and a higher ceiling and a greater rate of climb than previous models. Armament remained at four MG 17 machine guns; attempts to mount an MG FF 20mm cannon firing through the propeller hub were unsuccessful. Only a few Ds were produced: these were allocated to certain Zerstörer heavy fighter Gruppen as a stopgap until sufficient Bf 110s became available to equip them.

The D was followed by the E subtype, which became the first major mass-production machine. This was powered by the DB 601, which featured variable-speed supercharging, had fuel injection instead of a carburettor and was rated at 1,100hp. This gave greatly improved performance—a maximum speed of 354mph at 12,300ft, an initial climb rate of 3,100ft/min and a service ceiling of 36,000ft. Fuel injection meant that negative-g manoeuvres could be made without the engine cutting—a tremendous advantage in combat. The two nose machine guns were retained, but the wing machine guns were replaced by 20mm MG FF cannon, to give a large increase in hitting power. Wing loading, at 321b/ sq ft, was fairly high for a single-seat fighter at that time, and turning ability was comparatively modest.

The third Luftwaffe fighter type to see action in Poland was the Messerschmitt Bf 110. Designed as a long-range escort fighter, it first flew in May 1936, a year later than the 109. Although this aircraft was far less manoeuvrable than, and had an acceleration inferior to, its single-engine sibling, trials in 1937 showed it to be appreciably faster than the Bf 109B which was currently in production. This, plus the perceived need for a long-range fighter to escort bombers deep into enemy territory, ensured its eventual adoption by the Luftwaffe.

The Bf 110B-1 was powered by two DB 600A liquid-cooled inline engines and was very heavily armed, with a battery of two 20mm MG FF cannon plus four 7.9mm MG 17 machine guns in the nose. The need for long-range radio communications resulted in a second crew member being carried; in combat he provided a rearward lookout and gave a modicum of rearward protection with a swivelling 7.9mm MG 15 machine gun.

With the advent of the superior DB 601 engine, production of the B-1 was halted in favour of the C-1, which was powered by this unit. Other changes embodied extensive structural strengthening, and a slightly reduced wingspan. The maximum speed of the C-1 was 336mph at 19,686ft; initial climb rate was 2,165ft/min, service ceiling 32,810ft and wing loading at maximum all-up weight a moderate 331b/sq ft.

The first Jagdflieger action of the war occurred on 1 September, when P.11 cs and P.7s of the Pursuit Brigade encountered Heinkel bombers heading for their airfield at Okecie. The escorting Bf 110s of I(Z)/LG 1 were slow to react but eventually accounted for two P.7s, although their Kommandeur, seven-victory Spanish Civil War veteran Walter Grabmann, was wounded in the action. This was hardly a promising combat début for the Zerstörer.

That afternoon I(Z)/LG 1 was again in action, this time while escorting bombers over Warsaw itself. Led in Grabmann’s absence by Hauptmann Schlief, they tangled once more with the Pursuit Brigade. The initial bounce from above failed, but then the Germans tried the decoy trick, one of the oldest in the book (Fig. 7). A single 110 slipped away on its own, flying slowly and uncertainly. A P.11 pounced on it, only to fall to the lurking Schleif’s guns. Four more Polish flyers were decoyed and shot down in this way before the action was broken off.

The correct tactics against the lightly wing-loaded Polish fighters were dive and zoom, or high-speed slashing attacks, but often the temptation to start turning with them proved too much. This was not a good idea. On the afternoon of 2 September about twenty Bf 110s of I/ZG 2 clashed with six P.11s, two of which were shot down, one by future night fighter Experte Helmut Lent, but at a cost of three of their own. While the Polish fighters might be technically outclassed it was yet another matter to underestimate the skill of the man in the cockpit, and an error of the first magnitude to fight on his terms.

In a matter of days the air battle for Poland had been decisively won by the Luftwaffe. Most of the escort missions were carried out by the Bf 110 Gruppen: the shorter-legged Bf 109s were mainly employed on defensive duties. This apart, the German top scorer of the Polish campaign was Hannes Gentzen, Kommandeur of the Bf 109D-equipped I/ZG 2, with seven victories, consisting of two fighters and five bombers. No other German fighter pilot attained five victories.

The Polish campaign was notable for the number of future Experten who scored their first victories there. Among these were Bf 110 pilots Wolfgang Falcke of I/ZG 76, with three victories, and Gordon Gollob, later to become the first man to score 150 victories, of the same unit. Bf 109 pilots who later became famous were Hans Phillipp of I/JG 76, Erwin Clausen and Fritz Geisshardt of I(J)/LG 2 and Gustav Rödel of I/JG 21.


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