After Soviet failures in the Winter War, Rokossovsky was reinstated due to an urgent need of experienced officers. Following Germany's invasion of the Soviet Union, Rokossovsky played key roles in the defense of Moscow and the counter-offensives at Stalingrad and Kursk. He was instrumental in planning and executing part of Operation Bagration—one of the most decisive Red Army successes of the war—for which he was made Marshal of the Soviet Union.