The Soviet order of battle for the invasion of Poland in 1939 details the major combat units arrayed for the Soviet surprise attack on Poland on September 17, 1939. As a result of joining battle after the Germans had already launched their invasion, the Soviets, prepared for battle in secrecy, met comparatively limited resistance. Several skirmishes between the German and Soviet forces did occur, but neither government was prepared for starting a larger conflict, and these were soon referred to as "misunderstandings".^[1]

Like the Germans, the Soviets employed two primary offensive axes, each managed by a Front. Each Front commander had at his disposal a mobile group of forces created from cavalry and mechanised troops; a precursor of the cavalry-mechanised groups of the Second World War.

The effects of the purge are visible in the ranks of the commanders in the order of battle, with only one Army commander serving in the appropriate rank of Komandarm, in this case 2nd Class (Komandarm 2nd rank, Russian: командарм 2 ранга), the rest serving in being Corps (Komcor) and Divisional (Komdiv) Commander rank (Russian: комкор, комдив)