with the victory at tuchola forest, the danzig corridor was broken through and the 3rd and 4th armies could connect. xix army corps now moved some 70 kilometers east, towards kwidzyn, whereas 218th infantry division was called up from army group north's reserves to continue to fight the remaining polish resistance in the tuchola forest. with that redeployment, xix army corps, now operating east of the vistula, was to cover the left flank of von küchler's 3rd army."" küchler's forces had their main strength concentrated in the nidzica-wielbark area and had been met with fierce resistance by well-entrenched polish defenders of the modlin army who benefitted from the swamps and forests north of mława and przasnysz. the polish defensive line was taken on 6 september, crossing the narew river at różan "(see also battle of różan)." the 3rd and 4th armies were now to line up along the vistula river to strike at warsaw from the north.""