in 1984, Hirohito Tennō Itsutsu no Ketsudan ("Emperor Hirohito's Five Decisions"), attracted the attention of Marius Jansen, who arranged to have it translated into English as Hirohito: The Showa Emperor in War and Peace. According to Edward Drea, on the question of "whether the emperor was really Japan's ruler and power-holder or merely a puppet and robot ... [Hata] concludes that the answer to this complex question lies somewhere in between, although Hata credits Hirohito with considerable political savvy." Apart from Drea the book also garnered highly positive reviews from Stephen S. Large and Hugh Cortazzi. Nankin Jiken and Nanjing Massacre death toll estimates Hata's major contribution to Nanjing (Nanking) Massacre studies is his book Nankin jiken ("The Nanking Incident"), published in 1986, which is a detailed study of the event based on Japanese, Chinese, and English sources that was later noted by historians such as Daqing Yang to be one of the few impartial works of scholarship written on the massacre during the period. The book is known for its relatively low estimate of the death toll, which Hata put at up to 40,000 because he based the number of civilian killing on the work of Lewis S. C. Smythe who conducted a survey of the massacre in the immediate aftermath (War Damage in Nanking Area, Dec.1937 to March 1938, Urban and Rural Surveys) and also exclude Chinese soldiers. Hata's book is acknowledged as the first to discuss what might have caused the massacre, whereas previous books had focused only on the event itself. Hata argued that the Japanese Army's lack of military police and facilities to detain POWs, its ignorance of international laws, and the Chinese General Tang Shengzhi's decision to flee the city without formally surrendering, which left large number of plain-clothes soldiers within the civilian population which was followed by excessive mopping-up operations by the Japanese, among the factors which led to the slaughter. Some contemporary researchers including the historian Tomio Hora and the journalist Katsuichi Honda expressed strong disagreement with Hata's death toll estimate, though both expressed admiration for Hata's scholarship and sincerity. Hata is today recognized as the major scholar of the so-called "centrist" school of thought on the Nanjing Massacre, which in terms of the death toll believes that tens of thousands were killed and thus stands between the "great massacre" school which believes that hundreds of thousands were killed, and the "illusion"