Sapper army

The Soviets hoped such works would strengthen Red Army defensive operations and buy enough time to rebuild their forces for a counter-offensive.

The sapper armies were not only composed of military personnel; "women, old men, schoolchildren and teenagers under the draft age"[3] were also mobilized to serve in the construction units.

The sapper armies worked to construct defensive lines that were made up of battalion and company strong points in the Moscow, Stalingrad, North Caucasus, and Volga military districts.

Dissatisfied with the relative lack of flexibility of the sapper armies, the high command disbanded five of them in February 1942 and used the released personnel for the formation of new rifle (infantry) units.

Confronted with the German summer offensive of 1942, the remaining sapper armies built defensive works around Moscow and Stalingrad, and in the Caucasus.