After 27 September, much of the fighting in the city shifted north to the industrial district. Having slowly advanced over 10 days against strong Soviet resistance, the 51st Army Corps was finally in front of the three giant factories of Stalingrad: the Red October Steel Factory, the Barrikady Arms Factory and Stalingrad Tractor Factory. It took a few more days for them to prepare for the most savage offensive of all, which was unleashed on 14 October with a concentration of gunfire never seen before.