The U.S. Occupation authorities in Japan at first banned the teaching of Japanese history. After the ban was lifted in November 1946, school textbooks referred routinely but briefly to the Nanjing Massacre. These references disappeared from about 1955 with the stigmatizing of Marxist historians who were critical of "imperial myths and morals" during the Cold War. The "spirit of patriotism" was to be written into school textbooks, to take the place of the "red textbooks" which were critical of the state and the Emperor. The Nanjing Massacre was written out of Japanese textbooks completely from the 1950s to 1970s, until disgust with the Vietnam War led Japanese society to rethink Japanese militarism in the World War II period. Katsuichi Honda's 1971 "Travels in China" was a keystone of this reexamination of the war era.