The national identity has become so unfortunately bound up with demonstrations against Japan. So we turn from recent differences to subjects less timely. The horrors of the Nanjing massacre of 1937 have long stoked the imagination of Chinese artists. In just the past three years, two films have tackled the subject: Zhang Yimou’s “The Flowers of War” and “City of Life and Death” by Lu Chuan (on the film’s set, above). Neither director shies away from presenting the brutality of the Japanese army, who, on invading the city, murdered hundreds of thousands of people. But one difference proved crucial to the films’ longevity at the box office. The patriotic “Flowers” became the highest-grossing Chinese film of 2011. Mr Lu’s film, which cast a Japanese soldier in a nuanced light, fared well in terms of ticket sales initially but was pulled from screens prematurely, without having time for its natural run. The film-maker’s gesture of sympathy towards the Japanese side stirred too much controversy.