The Poles held the Old Town until a decision to withdraw was made at the end of August. On successive nights until 2 September, the defenders of the Old Town withdrew through the sewers, which were a major means of communication between different parts of the Uprising. Thousands of people were evacuated in this way. Those that remained were either shot or transported to concentration camps like Mauthausen and Sachsenhausen once the Germans regained control. Soviet attacks on the 4th SS Panzer Corps east of Warsaw were renewed on 26 August, and the Germans were forced to retreat into Praga. The Soviet army under the command of Konstantin Rokossovsky captured Praga and arrived on the east bank of the Vistula in mid-September. By 13 September, the Germans had destroyed the remaining bridges over the Vistula, signalling that they were abandoning all their positions east of the river. In the Praga area, Polish units under the command of General Zygmunt Berling (thus sometimes known as "berlingowcy" – "the Berling men") fought on the Soviet side. Three patrols of his First Polish Army () landed in the Czerniaków and Powiśle areas and made contact with Home Army forces on the night of 14/15 September. The artillery cover and air support provided by the Soviets was unable to effectively counter enemy machine-gun fire as the Poles crossed the river, and the landing troops sustained heavy losses. Only small elements of the main units made it ashore (I and III battalions of 9th infantry regiment, 3rd Infantry Division). The limited landings by the 1st Polish Army represented the only external ground force which arrived to physically support the uprising; and even they were curtailed by the Soviet High Command due to the losses they took. The Germans intensified their attacks on the Home Army positions near the river to prevent any further landings, but were not able to make any significant advances for several days while Polish forces held those vital positions in preparation for a new expected wave of Soviet landings. Polish units from the eastern shore attempted several more landings, and from 15 to 23 September sustained heavy losses (including the destruction of all their landing boats and most of their other river crossing equipment). Red Army support was inadequate. After the failure of repeated attempts by the 1st Polish Army to link up with the resistance, the Soviets limited their assistance to sporadic artillery and air support. Conditions that prevented the Germans from dislodging the resistance also acted to prevent the Poles from dislodging the Germans.