December, the operation was approved by the Stavka and received the codename "Iskra" (Spark). The operation was due to begin in January 1943. By January 1943, conditions were improving for the Soviets. The German defeat in the Battle of Stalingrad had weakened the German front. The Soviet forces were planning or conducting offensive operations across the entire front, especially in southwestern Russia. Amidst these conditions, Operation Iskra was to become the first of several offensive operations aimed at inflicting a decisive defeat on Germany's Army Group North. Preparations The area south of Lake Ladoga is a heavily forested area with many wetlands (especially peat deposits) close to the lake. The forest shielded both sides from visual observation. Both factors greatly hindered the mobility of artillery and vehicles in the area, providing a considerable advantage to the defending forces. The Sinyavino heights were a key location, with terrain higher than the surrounding flat terrain. Because the front line had changed very little since the blockade was established, German forces had built an extensive network of interconnected trenches and obstacles, interlocking artillery and mortar fire. The Neva River was partially frozen, allowing infantry to cross. German preparations The Germans were well aware that breaking the blockade was very important for the Soviet side. However, due to the reverse at Stalingrad and the Soviet offensive at Velikiye Luki to the south of Leningrad, Army Group North was ordered to go on the defensive and was stripped of many troops. The 11th Army, which was to lead the assault on Leningrad in September 1942, and which had thwarted the last Soviet offensive, was transferred to Army Group Center in October. Nine other divisions were also reassigned to other sectors. At the start of the Soviet offensive, the German 18th Army, led by Georg Lindemann consisted of 26 divisions spread across a wide front. The army was stretched very thin and as a result had no division-level reserves. Instead, each division had a tactical reserve of one or two battalions, and the army reserves consisted of portions of the 96th Infantry Division and the 5th Mountain Division. The 1st Air Fleet provided the air support for the army. Five divisions and part of another one were guarding the narrow corridor which separated the Soviet Leningrad and Volkhov Fronts. The corridor was only wide and was called the "bottleneck". The German divisions were well fortified in