Here's a brief history of this gruelling battle against all odds...

Luftwaffe order of battle included Luftflotte 1 and Luftflotte 4 which on September 1st consisted of 1538 combat aircraft. Of these, 339 were Messerschmitt Bf 109 fighters, mostly the 109E (Emil) variant, 82 Messerschmitt Bf 110 twin-engine fighters and 258 Junkers Ju 87 Stuka dive-bombers. The remaining number were various subtypes of Heinkel He 111 and Dornier Do 17 bombers, there was also a Staffel of Henschel Hs 123 ground attack planes. Additionally, some 102 Bf 109 fighters formally assigned to the defence of the Reich were also used, though on limited scale. 202 reconnaissance aircraft were assigned to the army units involved in the assault, which brings us to the total of 1942 combat aircraft used operationally against Poland. Replacements and reinforcements of over 100 aircraft in total were brought in at various stages of the campaign.

PZL P.37 bomber and P.11 fighters at Okecie airfield prior to war

Polish Lotnictwo Wojskowe order of battle included two large units, the Pursuit Brigade (Brygada Poscigowa) and the Bomber Brigade (Brygada Bombowa), both under the command of the General Staff, as well as the Army Air Force (Lotnictwo Armijne) which consisted of individual wings (dywizjony) and squadrons (eskadry) assigned in groups to seven different Polish Army commands. The Pursuit Brigade, comprised of five fighter squadrons with the total of 53 aircraft , was given the task of defending Warsaw and its environs. The Bomber Brigade, with 36 excellent  medium bombers, and  light bombers constituted a considerable force, but outdated concepts of air warfare adhered to by the Polish command severely limited its effectiveness. In total, in its hour of need, Poland was able to muster 404 first-line aircraft, of which only 308 had any combat value. Of these, 128 were PZL P.11 fighters, all 3 to 5 years old which, sturdiness and maneuverability notwithstanding, had very limited performance compared to their German counterparts. The rest of the fighters in first-line units - 30 a aircraft - were totally obsolete. The 36  Los bombers were the only equipment on par with the Luftwaffe, and the 114  reconnaissance/light bomber aircraft could be considered barely adequate for the time.

The remains of a Do 17 shot down by Wladyslaw Gnys on 1 September 1939

The first clash between Luftwaffe and Polish fighters took place on September the 1st, shortly before 7 am over the secret Polish airfield of Balice, near Cracow. A three-airplane section of  was surprised during take-off by three Ju 87s and Capt. Medwecki, the Commanding Officer of the Cracow Army Fighter Wing was killed. His victor was Franck Neubert of StG2 Immelmann. 2nd Lt. Wladyslaw Gnys managed to evade the attack, and damage one of the Stukas. A few minutes later, having climbed, he attacked two Do 17s returning from a raid on Cracow, scoring several hits on each of them. After his second dive, he lost visual contact with them and returned to the airfield not knowing that he had just scored the first two victories over Luftwaffe in World War 2. The two German bombers collided after his attack and fell to the ground near the village of Zurada.

Meanwhile, a far bigger engagement was to take place over the outskirts of Warsaw. Alarmed by the well-organized network of observation posts, the Pursuit Brigade in full force (52 aircraft) intercepted a large formation of He 111 bombers from KG27 escorted by Bf 110s of I/LG1. As a result of well-executed attack, six He 111s were shot down at the expense of one P.11c, which crashed during a forced landing. What was supposed to be Der Spaziergang uber Warshau - a 'stroll over Warsaw' - turned into a bitter escape for the Luftwaffe bomber crews. During the fighting, 2nd Lt. Borowski of 113 Eskadra shot down a stray Bf 109, which became the first aircraft of that type destroyed in World War 2.

Heavy fighting over Warsaw resumed in the afternoon, when second large German raid, escorted by both Bf 110 and Bf 109 fighters, was intercepted by the Pursuit Brigade. This time the escorts were able to engage Polish fighters before they reached the bombers, and soon first German bombs fell on Warsaw. Before they were able to enter the fight, four of 123 Eskadra were shot down in a surprise attack by Bf 110s of I/LG1. Capt. Olszewski, the C/O was killed and the other three pilots baled out, two of them shot at and heavily wounded by the Germans after opening their parachutes. These were the first victories for German fighter pilots in World War 2.The fighting was fierce, and Germans lost two Bf 109s, one of them shot down by Lt. Col. Leopold Pamula, deputy C/O of the Brigade, who himself had to bale out soon afterwards. Polish losses amounted to three P.11s.
 

September 25 - Warsaw is burning after heavy bombardment

In the following days, the Luftwaffe changed its tactics. Taking advantage of the superior characteristics of its aircraft (German twin-engined bombers were faster than Polish fighters), it used small groups of bomber aircraft approaching the target from several directions at different altitudes, while Bf 109s and Bf 110s flew sweeps in the area. These tactics proved quite successful - despite its valiant efforts, the Brigade was unable to prevent German bombs from falling on Warsaw. Its pilots managed to shoot down 47 German planes from 1 to 6 September, but combat attrition was very high, and on September 7 the remnants of the Brigade were moved to the Lublin area, leaving the capital virtually defenseless against heavy Luftwaffe raids (Warsaw was never captured by the Germans - it was to be bombed into submission during 20 days of successful defence against German assault). 

In other parts of the country the Army fighter units fought with varying degrees of success. As they were lacking the observation facilities of the Pursuit Brigade, they either flew sweeps, or detached small formations of fighters to improvised airfields with the task of intercepting sighted German aircraft. The latter tactic, called 'ambushes', was soon abandoned, as the P.11 fighters were usually unable to intercept their targets, no matter how quick the take-off.
 

The wreckage of Capt. Laskowski's P.11

The often desperate situation of Polish ground units sometimes resulted in equally desperate measures taken by the supporting air forces. On September 2nd, the Pomorze Army Fighter Wing was ordered to strafe a German motorized column making a quick advance into Polish territory near Grudziadz. As the P.11 fighters were totally unsuitable for the task, armed only with two (a few aircraft had four) 7.92mm machine guns and offering no armor protection, the C/O, Capt. Florian Laskowski decided that while he would lead 141 Eskadra to attack the troops, 142 Eskadra would fly a regular fighter sweep. When nine P.11s of 141 Eskadra approached the target, they were met by heavy machine gun fire and soon three planes were shot down, their pilots killed. Among the casualties - and first to be downed - was Capt. Laskowski. Another pilot had to make a forced landing, all the other planes took scores of hits. Needless to say, the effect of the attack on the Germans was marginal at best. Meanwhile, 142 Eskadra intercepted two unescorted German raids in succession and claimed 7 victories, with no losses on its part.
 

A Bf 110 shot down in September 1939

Not surprisingly, combat attrition proved high for Army fighter squadrons, and by September 10 all but one Army fighter wings were moved east of Vistula, where a futile attempt to rebuild the Pursuit Brigade and charge it with the defence of Lublin area was being made. Faced with fuel and spare parts shortages, devoid of any organized observation network, these pilots fought only isolated skirmishes with the Luftwaffe, claiming but 5 victories till September 17th. On that day the Red Army crossed Poland's eastern borders, and all the remaining aircraft were ordered to fly to Romania. The only Dywizjon that remained with its Army was the Poznan Army Fighter Wing. Under the excellent command of Mjr. Mieczyslaw Mumler, it was able to fight effectively, up to September 17th, scoring no fewer than 36 kills throughout the campaign. This in spite of the fact that on 9th September Mjr. Mumler was forced to disband 131 Eskadra and transfer its remaining aircraft to 132 Eskadra, (it was also reinforced by three pilots from the disbanded unit, the rest simply had no aircraft to fly).

While their colleagues of the fighter squadrons were busy trying to fight off swarms of enemy aircraft, the crews of the Bomber Brigade spent the first two days of September in readiness, waiting for orders to take-off - which never came. There was a great deal of confusion in the Brigade headquarters, and aside from reconnaissance no missions were flown. As the Polish command had promised their West-European allies not to bomb any targets on German territory, it was decided that the Brigade would support ground troops by attacking enemy motorized and Panzer columns. Little thought was given to attacking enemy airfields or supply lines, which would definitely have been more effective in delaying German advance. Thus, beginning on September 3rd, the Brigade's P.23s and - on the next day - P.37s started flying bombing missions against advancing German troops. Surprisingly enough, these actions enjoyed a reasonable success. Attacks on German Panzer columns near Radomsko on September 3rd, carried out by some 30 P.23s of the Brigade, stopped their advance for about two days. While other actions weren't nearly as successful, over all the attacks proved enough of a nuisance that the Luftwaffe was forced to provide fighter patrols for covering the advancing troops. However, the tactics of nuisance attacks in small formations (usually of three aircraft) and strafing the columns after dropping the bomb load (crews had specific orders to do so) in aircraft unsuitable for the task quickly proved very costly. Devoid of fighter escort, many bombers fell to the guns of patrolling Bf 109s, while more yet were shot down or heavily damaged by anti-aircraft fire. Even so the missions were carried out till the Brigade was left with virtually no aircraft. On September 17th only 17 P.37s of Brigade's initial strength of 86 aircraft flew to Romania, all the P.23 Karas bombers having been either destroyed or damaged beyond repair.
 

A crash-landed P.23 of 41 Eskadra

Life wasn't much easier for Army reconnaissance squadrons which, armed with the same P.23 light bombers as the Brigade, often took up ground support missions, trying to relieve at least some of the relentless pressure experienced by the ground units. Again, these actions did enjoy a limited success. On September 2nd, P.23s of 24 Eskadra escorted by 6 P.11s from 122 Eskadra - an extremely rare comfort for Polish bomber crews - totally surprised a German column near Czestochowa, causing many casualties and heavy confusion. On the next day crews from the same Eskadra successfully bombed German Panzer column near Rabka, scoring direct hits on several tanks. Only one P.23 was lost in these attacks, but that, again, was to prove an exception rather than the the rule. In a similar attack on September 3rd, 31 Eskadra - even though its six P.23s caught Germans unaware during a rest and caused heavy casualties - lost two aircraft, the remaining four were more or less seriously damaged. Reconnaissance missions, usually flown by single aircraft, were also dangerous - Luftwaffe's dominance in the air was evident and the crews could rarely count on help from Polish fighters. In general, combat attrition was extremely high and only 16 of the initial 64 P.23s from the army reconnaissance squadrons made it to Romania on September 17th.

Of about 2000 aircraft used against Poland Luftwaffe lost 258 to all causes, and of additional 263 damaged only 40% made it back to the front-line units after repairs. An estimated 230 aircraft were destroyed in action, primarily by Polish fighters and anti-aircraft artillery. About 400 aircrew were killed or missing, and an additional 120 wounded. Of 217 German tanks destroyed and 457 seriously damaged in the campaign, a significant proportion can be attributed to the Bomber Brigade and P.23s of the Army reconnaissance squadrons.

Lotnictwo Wojskowe lost 333 aircraft, 260 as the result of enemy action. Of these, around 100 were destroyed in combat, and a further 120 as the result of sustained damage. Only 25 combat aircraft (as opposed to many training and civilian airplanes) were destroyed on the ground. Aircrew killed numbered 61, 110 were missing and 63 wounded. When comparing the combat potential of both sides, this is by no means a bad result for the Polish Air Force.

An interesting observation is that, throughout the campaign, more than 30 Polish aircraft were shot down by Polish anti-aircraft fire. This sad testimony to the efficiency of Polish AA gunmen (who also took a heavy toll - considering the minute number of AA guns available - of the Luftwaffe) is easy to explain. Constantly harassed by the Luftwaffe, mauled by the horrifying Stuka attacks, Polish ground troops fired at anything that flew. Polish aircraft were indeed a rare sight those days, thus, when they did appear, they were almost automatically assumed to be German. Probably the worst incident happened on September 8th. When P.11s of III/2 Dywizjon were chasing a He 111 formation near Pulawy, Polish AA opened fire, and shot down four aircraft, killing two pilots - one of them the C/O of 121 Eskadra - and wounding one. More frequent, though, were cases of downing Polish liaison and reconnaissance aircraft, which, because of German mastery of the air, usually kept close to the ground and were often hit by own machine gun or even small arms fire.

Another interesting statistic is the number of defensive kills by Polish bomber and reconnaissance crews - 14 - as compared to the number of these aircraft shot down by German fighters, which is 31. As Polish bombers had relatively weak defensive armament (three 7.92mm guns) and no armor, even assuming top-quality gunnery on part of the Polish crews, there is no escape from the conclusion that many German fighter pilots were only learning their trade (for comparison: the Pursuit Brigade claimed 38 victories over German bombers and lost only 4 fighters to their defensive fire).