In August 1939, Tanaka was assigned as commander of the IJA 13th Division, and spent the following year in combat on the front lines during the Second Sino-Japanese War, especially the Battle of Wuhan and the Battle of Zaoyang–Yichang. In 1940, he was awarded both the Grand Cordon of the Order of the Rising Sun and the Grand Cordon of the Order of the Sacred Treasure. He returned to Japan to resume his post as commandant of the Kempeitai in September 1940.