After the Polish capitulation following the Soviet Invasion of Poland on 17 September 1939, ZG 76 reorganised in the Phoney War period. II. and III./ZG 76 finally were able to convert from the Bf 109 to Bf 110 and shed their "Jadggruppe" designations. ZG 76 flew protection patrols (Defence of the Reich) over the German North Sea coast in late 1939. Elements of it took part in the Battle of the Heligoland Bight on 18 December 1939 and the wing claimed five Vickers Wellington bombers shot down. RAF losses were 12 bombers destroyed, three damaged and 57 men killed, though German claims were far higher.