civilians trapped in Breslau in addition to the German soldiers, according to German historian Rolfe Hinze. With the city having been declared a fortress, thousands of forced laborers from local prisons and concentration camps were brought in to build defenses and clear rubble. Many would be executed or would die in the crossfire. Siege The infantry units of the 6th Army consolidated the advances of the 7th Guards Mechanized Corps between 14 and 16 February, solidifying the inner ring of the siege. The 7th Guards Mechanized Corps was withdrawn on the night of 15 February due to a German counterattack in the Strigau area; by the evening of 14 February, Korchagin's command was down to 108 T-34s, nine ISU-122s, seventeen SU-85s, and thirteen SU-76s, showing its heavy losses in the encirclement of Breslau. In preparation for the transfer of the 5th Guards Army to another sector, its 294th Rifle Division, advancing on Breslau from the east, was transferred to the 6th Army. The latter also received the 77th Fortified Region from the 52nd Army, which defended the northern bank of the Oder. Beginning on 18 February, the 273rd Rifle Division and the reserve regiments of the 6th Army began relieving the units of the 5th Guards Army to the southeast of Breslau; the composition of the 6th Army remained unchanged for the rest of the siege. The 6th Army besieged the city with the 22nd and 74th Rifle Corps, and the 77th Fortified Region, as well as other smaller units. 50,000 German troops defended the city. Meanwhile, 22nd Rifle Corps commander Major General Fyodor Zakharov ordered his unit at midday on 14 February to capture the southwestern part of the city and advance to the city center by the end of the day. However, the corps' attacks on the Breslau outskirts in the following days proved unsuccessful. The 309th overcame the Lohbrück–Opperau line, while the 218th Rifle Division took Krietern; the German resistance rendered a speedy advance to the city center in a day unfeasible. The 218th began an attack on the key railway embankment in the southwest of the city on 18 February and captured it on the next day, bringing the Soviet forces within two miles of the city center. The 667th Rifle Regiment of the 218th advanced into the Südpark but was forced to retreat back to the railway line on 20 February by a counterattack of