By late July, Army Group North positioned 4th Panzer Group's units south and east of Narva, Estonia, where they could begin an advance on Leningrad in terrain conditions relatively suitable for armoured warfare. By that time, however, the army group lacked the strength to take Leningrad, which continued to be a high priority for the German high command. A compromise solution was worked out whereas the infantry would attack north from both sides of Lake Ilmen, while the panzer group would advance from its current position. Hoepner's forces began their advance on August 8, but the attack ran into determined Soviet defences. Elsewhere, Soviet counter-attacks threatened Leeb's southern flank. By mid to late August, the German forces were making gains again, with the 4th Panzer Group taking Narva on 17 August.