during much of the sino-japanese war, chang served as minister of communications, accompanying the central government from nanking to chungking. after mid-1943, he was in the u.s. frequently promoting aid to the republic of china and at the negotiations of post-war arrangements, including aviation rights. he wrote a book on railroad development which was published in the u.s. at a time when interest in china was high. after the war, he was appointed economic commissioner for manchuria, and his diaries from this period were also published in the u.s.