Division from the 3rd Panzer Group arrived at Yartsevo behind Smolensk. The next day motorized infantry from the 2nd Panzer Group forced most of the Soviet defenders from Smolensk, reducing the gap between 2nd and 3rd Panzer Groups to less than 20 kilometers. The 16th, 19th and 20th Soviet armies were threatened with impending encirclement and now strung out along the north bank of the river contained in a triangle between Vitebsk to the north-west, Yartsevo to the north-east, and Smolensk to the South. With his front rapidly deteriorating Timoshenko released Rokossovsky from 4th Army (a command he had assumed in name only) and gave him the task of assembling a stopgap formation to be called "Group Yartsevo" that would deal with the emergency presented by the sudden appearance of the 7th Panzer at Yartsevo. This ad hoc operational group was to defend the bridgeheads of the Vop river, a tributary of the Dnepr, and prevent the southern and northern wings of the Panzer envelopment from converging at the Dnepr. Collapse seemed imminent. Stalin, unmoved, reiterated his demand to Timoshenko that Smolensk should not be surrendered and called the "evacuation attitude" of the front-line commanders of the besieged armies criminally "treasonous". Rather than retreat, Timoshenko's armies would stand their ground and attempt to recapture Smolensk. "Group Yartsevo" was in theory a large army-sized formation, but when Rokossovsky arrived at Timoshenko's headquarters on the evening of the 17th, he was in fact in charge of his own small staff, two quad anti-aircraft machine guns mounted on trucks and a radio van. At first, Rokossovsky had to resort to pulling together a fighting group from reserve units and retreating stragglers, but over the coming days it became a more substantial force. Retreating regiments and divisions from the 44th Rifle Corps filtered out of the Smolensk pocket and were transferred to his command and fresh forces arrived from the reserve—the 107th Tank Division (formerly the 69th Motorized Division from the Trans-Baikal Military District) and the 101st Tank Division equipped with 220 outdated but functional tanks. What commenced was a confusing seesaw battle for control of Smolensk that saw portions of the city change hands several times over the next week, while Rokossovsky's group held the back door open and harassed the advanced German panzer formations. Day by day, Rokossovsky's forces became stronger. As the Smolensk pocket deflated under German pressure Rokossovsky was able