Further promotions for Ishii would follow; he was promoted to Senior Army Surgeon, First Class (surgeon colonel) in 1938, Assistant Surgeon General (surgeon Major General) in March 1941, and Surgeon General (surgeon Lieutenant General) in March 1945. Towards the end of the war Ishii would develop a plan to spread plague fleas along the populated west coast of the US, known as Operation Cherry Blossoms at Night. This plan was not realized due to the surrender of Japan on August 15, 1945. Ishii and the Japanese government attempted to cover up the facilities and experiments, but ultimately failed with their secret university lab in Tokyo and their main lab in Harbin, China. The Japanese Army's Unit 731 War Crimes Exhibition Hall (731罪证陈列馆)[ex] in Harbin stands to this day as a museum to the unit and the atrocities they committed.