Ten weeks seemed ample time. Churchill offered the USSR an alliance, and Roosevelt promised lend-lease aid, but after the first few days, their staffs believed everything would be over in a month or so. By the end of the first week in July, Army Group Center had taken 290,000 prisoners in encirclements at Bialystok and Minsk. On August 5, having crossed the Dnieper River, the last natural barrier west of Moscow, the army group wiped out a pocket near Smolensk and counted another 300,000 prisoners. On reaching Smolensk, it had covered more than two-thirds of the distance to Moscow.