In an anonymous section of a report on the Spanish Civil War, Kulik noted that tanks not facing anti-tank weaponry were effective on the battlefield. He and Voroshilov argued that Tukhachevsky's theoretical style of warfare could not yet be carried out by the Red Army in its pre-war state, even if those theories were effective. Though Tukhachevsky was purged in 1937 because of Stalin and Voroshilov's dislike for him, his theories were at that time already widely influential in the Red Army. Though Kulik and Voroshilov's reforms moved the Red Army further away from deep operations doctrine, which had fallen out of favor due to many of its proponents being purged, as well as a lack of officers able to carry out the complicated operations required, the adjustment of Soviet military theory to better reflect the Red Army's actual operational capability would a positive impact of the performance of the army in the opening days of WWII. Marshal Georgi Zhukov's use of deep operations techniques techniques to great effect in Manchuria against the Japanese would eventually convince Stalin of their value, after which they were used effectively during Operation Bagration.