Several smaller offensives were launched in 1942 in the region, but failed. The last offensive near Lyuban resulted in the encirclement and destruction of most of the Soviet 2nd Shock Army. Nevertheless, the opening of a supply route to Leningrad was so important that preparations for the new operation began almost immediately after the defeat at Lyuban. The area south of Ladoga is heavily forested with many wetlands (notably peat deposits) close to the lake. This terrain hindered the mobility of artillery and vehicles. In addition the forest shielded both sides from visual observation. One of the key locations were the Sinyavino heights, which were approximately 150 metres higher than the surrounding flat terrain. The heights were one of the few dry and clear areas and provided a good spot for observation. The front line changed very little after the blockade was established, allowing the German forces to build a dense defensive network of strong points in the area, interconnected by trenches, protected by extensive obstacles and interlocking artillery and mortar fire. The plan to capture Leningrad in summer-autumn 1942 was first outlined in the OKW (German supreme command) directive 41 of April 5, 1942. The directive stressed that the capture of Leningrad and the drive to the Caucasus in the east were the main objectives in the summer campaign on the Eastern Front. During discussions with Hitler on June 30, the commander of Army Group North, Field Marshal Georg von Küchler, presented him with several operations that would help to carry out this directive. Following these discussions the OKH (German high command) started redeploying heavy artillery from Sevastopol, including the siege artillery batteries Gustav, Dora and Karl, to assist in destroying Soviet defenses and the Kronshtadt fortress. The redeployment was complete by July 23. On the same day, Fuehrer Directive No. 45 included orders for an operation by Army Group North to capture Leningrad by early September. This operation was named "Feuerzauber" (Fire Magic). The attack was to be carried out by the forces of the 11th Army, which were free to be used elsewhere after the capture of Sevastopol. In addition, the OKH sent the 8th Air Corps to provide air support for land forces. On July 30, the operation was renamed Operation Northern Light (). The formulated operation required three army corps to penetrate the Soviet defenses south of Leningrad. One corps would then cut off Leningrad from the troops to the south and west, while the other two would turn east and destroy the Soviet forces between the Neva River and Lake Ladoga.