The time difference, 04:40 versus 05:40, has been attributed by several writers, such as journalist Joachim Trenkner [pl], to a summer time-difference between Poland and Germany.

[3] Even if the time 04:40 was to be correct, several historians identify the first (aerial) action of the war as the bombing of the key Tczew bridge in the Pomeranian Corridor by bombers from Sturzkampfgeschwader 1 around 04:30.

[10][11] On 1 September 1939, 29 Junkers Ju 87B Stukas of I group Sturzkampfgeschwader 76, under command of Captain (Hauptmann) Walter Sigel,[12] took off from Nieder-Ellguth airfield.

[19] Two Dornier Do 17 reconnaissance planes that had surveyed the area between 04:50 and 05:02 for Polish military units, reported locating several, the nearest to the town being in a forest 12 kilometres (7.5 mi) southwest of Wieluń.

One of the latter waves, described by Piątkowski as the second, of Stuka bombers of I./Sturzkampfgeschwader 77, was commanded by Captain Friedrich-Karl Freiherr von Dalwigk zu Lichtenfels.

Norman Davies, who cited the number of "1,290 townspeople killed", common in older research, still relatively often reported in modern media, called the casualty rate "more than twice as high as Guernica's or Coventry's".

[3] Piątkowski writes that some historians, such as Grzegorz Bębnik and Marius Emmerling [pl], describe the bombings as having resulted from faulty reconnaissance or intelligence.

[13][27] German historian Jochen Böhler writes that the first operational report by Sturzkampfgeschwader 76 stated there had been "no enemy sightings", a finding corroborated by Poland's Institute of National Remembrance, which concluded there were no Polish military targets or units in the city or vicinity on 1 September or the preceding day—as had already earlier been stated as well by a number of historians.

[7] Historian Timothy Snyder suggests that the civilian population itself may have been the primary target: "The Germans had chosen a locality bereft of military significance as the site of a lethal experiment.

[29][30] Another view of a number of historians is that the destruction of the town infrastructure may have been the raids' aim, in order to test the tactics and firepower of the Luftwaffe, in particular of the new Ju 87B bomber.

Volkmann, like Böhler, observes that while Richthofen might not have intended it as a "terror attack", he had selected Wieluń as a target close to the border in order to test the capabilities and operational effectiveness of his dive bombers, if possible without losses to his own force.

As such, it is being compared to Guernica – a town destroyed in 1937 during the Spanish Civil War, no less but by the same Luftwaffe forces under the command of the field marshal Wolfram Freiherr von Richthofen.Targets destroyed by German bombing included: The city hall, with its 14th-century Kraków Gate, survived when a bomb got stuck in the city hall's roof and failed to explode.

In 2004 President Aleksander Kwasniewski unveiled a monument to the city's fallen residents, saying that "here total war was waged, not distinguishing between civilians and military, with the aim of mass extermination."

In 2017 President Andrzej Duda visited and "remind[ed] the world that the war started in Poland, on Westerplatte, but that in the first days the highest losses were sustained by civilians, and that Nazi Germany committed atrocities in bombing innocent populations.

[36] Two attempts, in 1978 and 1983, to prosecute individuals for the bombing of the Wieluń hospital were dismissed by West German judges when prosecutors stated that, in the morning fog, the pilots had been unable to make out the nature of the structure.