The Army was formed in May 1941 in the Leningrad Military District for the defence of the southernmost part of the Soviet Union's border with Finland, north and northeast of Vyborg.
From 31 July to the end of August in facing the Finnish offensive, it was unable to stop the Finns reconquering the Karelian Isthmus and thus the Army fell back to the old border line and occupied positions in the 22nd Karelian Fortified Region.
During the campaign, the army (more specifically the 43rd Rifle Division) was decisively defeated at the Battle of Porlampi.
The 23rd Army had suffered enormous losses in battles against Finns in July to August 1941.
[1] In August, the 14th Guards Rifle Corps was transferred to the Kharkov Military District.