Order No. 227 was an order issued on 28 July 1942 by Joseph Stalin, who was acting as the People's Commissar of Defence. It is known for its line "Not a step back!", which became the primary slogan of the Soviet press in summer 1942.

A penal military unit, also known as a penal formation, disciplinary unit, or just penal unit, is a military formation consisting of convicts mobilized for military service. Such formations may consist of military prisoners convicted under military law, civilian prisoners convicted in civilian courts, prisoners of war who have chosen to side with their captors, or a combination of these groups.