Initial Soviet forces committed by the Kalinin and Western Front included the 22nd, 29th, 30th, 31st, 39th of the former, and the 1st Shock, 5th, 10th, 16th, 20th, 33rd, 43rd, 49th, and 50th armies and three cavalry corps for the latter. The intent was for the 22nd Army, 29th Army and 39th Armies supported by the 11th Cavalry Corps to attack West of Rzhev, and penetrate deep into the western flank of Army Group Centre's 9th Army. This was achieved in January, and by the end of the month the cavalry corps found itself 110 km in the depth of the German flank. To eliminate this threat to the rear of the Army Group Centre's 9th Army, the Germans had started Operation Seydlitz by 2 July. However, due to the nature of the terrain the supply route of the troops of the Soviet 22nd Army, 29th Army and 39th Armies which attempted to enlarge the penetration became difficult, and they were encircled. The cutting of a major highway to Rzhev by the cavalry signalled the commencement of the Toropets–Kholm offensive.