In the wake of Operation Iskra, which broke the German land blockade of Leningrad in January, Marshal Georgy Zhukov conceived a plan to encircle and destroy Army Group North: Operation Polar Star. The first phase of the overall operation would be yet another attempt to cut off and eliminate the Demyansk salient. Zhukov finalized his plan during the week preceding the planned attack date of February 15, and the 11th and 27th Armies together had nine rifle divisions, including the 43rd Guards, plus 150 tanks, massed between Penno and Ramushevo against the 5th Jäger Division. However, in light of the encirclement and upcoming surrender of 6th Army at Stalingrad, on January 31 Hitler had authorized the evacuation of II Corps. Operation Ziethen began on February 17 before the delayed Soviet attack could get fully underway, and effectively short-circuited Zhukov's entire plan; 27th Army would still be redeploying as late as the 21st. Demyansk was abandoned that day and by February 26 most of the corridor was evacuated as well.