31st Army was formed with the following units: and on August 1, it was assigned to the Reserve Front, and added the following units:[1] The army was assigned to the Reserve Front on July 30, 1941, and it moved to the defensive line along Ostashkov - Yeltsy - Tishina River.
On October 6, it formed a task force under the command of Major General Polenov, and along with a task force from 19th Army under the command of Lieutenant General I. Boldin, was given the mission to break the enemy advance near Volokolamsk and Rzhev.
On October 7 the first snow fell, turning the roads into mud and forcing the 3rd Panzer Group's advance to a halt.
The snow allowed the army to set up defensive positions along the Zhuralyovo − Large Yakovtsevo − Ivashkova and create a corridor for retreating Soviet troops.
On January 7, 1942, troops of the 39th, 29th, 31st and 30th armies were stopped on prepared defensive lines north of Rhzev near Lotoshino.
On April 20, the army moved into defensive positions east of Zubtsov, Russia.
The army took part in the East Prussian Strategic Offensive under the command of the 3rd Belorussian Front.
The army was transferred to the 1st Ukrainian Front in order to participate in the Prague Offensive.
Composition at the end of World War II:[5] The army was disbanded in September 1945.