Founded in May 1939, the Geschwader (Wing) was a product of a late surge in expanding the size of the Luftwaffe medium bomber forces. The formation of the wing began on 1 May 1939 with the creation of the command (Stab) Gruppe (Group) and I. and II./KG 55 (first and second groups). III./KG 55 was formed on 1 November 1939 two months after the outbreak of war in Europe.