During the Second World War the German Luftwaffe was the main support weapon of the German Army (Heer). It fought and supported the Wehrmacht'''s war effort throughout the six years of conflict and contributed to much of Nazi Germany's early successes in 1939–1942. After the turn in Germany's fortunes, it continued to support the German ground forces until the German surrender in May 1945. Invasion of Poland On 1 September 1939 German forces invaded Poland, triggering World War II. The Luftwaffe begun the invasion by bombing the undefended town of Wieluń. The Luftwaffe was an instrumental component of the Blitzkrieg battle plan. The Luftwaffe assigned two airfleets to the campaign. Albert Kesselring's Luftflotte 1 was equipped with 807 aircraft, which was augmented by 92 Seaplanes of Fliegerfuhrer der Seeluftstreitkrafte. Alexander Löhr's Luftflotte 4 had 627 aircraft, augmented by 30 Slovak aircraft. A further 406 fighters were retained as part of home defence against potential Polish attack, while another 333 reconnaissance aircraft, under the command of Kommandeur der Luftwaffe, were attached to the army. The Junkers Ju 87 Stuka dive bombers carried out the first mission of the campaign, twenty minutes before war was officially announced. The dive bombers scored the first aerial victory of the war when Kettenführer Leutnant Frank Neubert shot down a Polish PZL P.11c fighter aircraft piloted by Captain Mieczysław Medwecki. The Polish Air Force was defeated in just over two weeks. The Poles had distributed their operational planes to satellite airfields, so what was left on the airfields was unserviceable aircraft which were then destroyed by the Luftwaffe which is where the incorrect statement that the Polish Air Force was destroyed on the ground originated from. The Polish bomber units did attempt to strike at the German Panzer (armoured) divisions and slow the speed of advance. Units equipped with PZL.37 Łoś bomber were destroyed within days. The Messerschmitt Bf 110 was proving itself to be more than capable in both the escort and bomber intercept role and accounted for the majority of these victories, which pleased Hermann Göring, a fan of the twin-engined heavy fighter. The Polish fighter units were still active, and were inflicting small losses on the Luftwaffe, however the Jagd and Zerstörergruppen were increasing their ground attack roles. As a result, many Polish fighters were caught taking off, when they were at a considerable disadvantage. It was indirect rather than direct air support