of 36 Ju 87s and the three Do 17Ps were available at Stolp-West, near Annafeld and Danzig by 1 September 1939. World War II Poland On 1 September 1939 the German Wehrmacht began the invasion of Poland followed sixteen days later by the Soviet invasion of Poland. Luftflotte 4 supported the 14th Army attacking out of Slovak Republic. Luftflotte 4's bombers dropped 389 tons of bombs on 1 September, 200 on Kraków in 1,200 sorties. Leutnant Frank Neubert and Unteroffizier Frank Kilnger from 1 Staffel are believed to have claimed the first aerial victory of the war against a PZL P.11. Captain Mieczysław Medwecki, 121 Squadron, Polish Air Force, was taking off from Balice airfield. Dinort led his Gruppe into action against airfields at Kraków and Katowice. Later in the morning Dinort led the group in the bombing of Wieluń, ostensibly to destroy a Polish Army cavalry unit reported in the town. German intelligence was wrong and Polish sources assert no Polish military unit was present. Dinort's I./StG 2 attacked the roads in the town; the bombing caused many civilian fatalities. Schmidt and Ulrich's Gruppen attacked other targets and were not involved. Schmidt was replaced by Hauptmann Claus Hinkelbein from 10 September. Counter air operations against the Polish Air Force failed since the Polish fighter force dispersed and succeeding in getting airborne. Along with elements of StG 77, I./StG 2 claimed the destruction of the Wołyńska Cavalry Brigade at the Battle of Mokra. Though it sustained 20 percent casualties the brigade was far from destroyed. On 3 September the Ju 87 groups under Richthofen's command contributed to the destruction of 7th Polish Division. Army Group North's operations were supported by the other Gruppen. The Polish Corridor and its elimination were the initial priority for the 4th Army, supported by Luftflotte 1. The targets were harbours, roads and bridges in the Danzig. III./StG 2 supported the Battle of Westerplatte and Battle of Danzig Bay. second and third group supported attacks on the Polish Navy, after ineffective assaults by the Kriegsmarine. II./StG 2 fought in the Battle of Radom until 9 September but little of its further service in Poland is known. I. and III./StG 2 assisted in the destruction of the Prusy Army at Radom. Two gruppen moved south toward I./StG 2. I. and III./StG 2 fought in the Battle of the Bzura. III./StG 2 attacked road and troop concentrations in