World War II in Europe began on Friday, 1 September 1939, when German forces invaded Poland. Wilcke, who at the time was still a member of 3. Staffel (3rd squadron) of JG 53, flew missions over Poland. He claimed his first aerial victory on 7 November 1939, over the Western Front when he shot down an Armée de l'Air (French Air Force) Potez 630, a twin-engined fighter, near Völklingen during the Phoney War. For this achievement he was awarded the Iron Cross 2nd Class () on 25 November 1939.
