 Lieutenant General Nikolai Gusev's 47th Army and Colonel General Vasily Chuikov's 8th Guards Army broke through the German defenses, and by 21 July they had reached the eastern banks of the Bug River.The following day, Lieutenant General Semyon Bogdanov's 2nd Tank Army began to advance toward Lublin and the Vistula river, while 11th Tank and 2nd Guards Cavalry Corps spearheaded a northwest push toward Siedlce, with the aim of preventing the retreat of Army Group Center forces which were fighting around the cities of Brest and Bialystok.Nazi concentration camp Maidanek near Lublin was liberated on 22 July.