一戰期間日本獨霸東亞,與中國簽訂一連串"中日密約"。戰后中日在巴黎和會就中國收回山東權益問題展開較量,北京政府原希望提出所有"中日密約",交由列強裁決,但中國代表團只提出與山東相關各約。當時正值上海南北和議召開,北京文治派與南方代表合作,藉英美列強對日本之猜忌及國民外交風潮,迫使武力統一派公布所有"中日密約",暴露皖系軍人與日本之密切關系。然而,最敏感之兩次購械合同并沒有公布,英美與日本對參戰軍及參戰借款之爭執也以妥協收場。

During the First World War,Japan dominated East Asia and signed a series of secret treaties with China. After the war,at the Paris Peace Conference,China and Japan were fighting for the issue of Shandong. The Beijing government had planned to publicize all the Sino-Japanese secret treaties and let the Powers to rule,but the Chinese delegation in Paris only publicized the treaties related to Shandong. Meanwhile,the South-North negotiation was held in Shanghai and the group of Beijing officials advocating peaceful unification collaborated with the representatives of the South,so they wanted to force the group of Beijing officials advocating military unification to publicize all the Sino-Japanese secret treaties to uncover the close relationship between the Anhui Clique of warlords and Japan. However,the most sensitive two contracts of weapon purchase were not publicized and the controversy of the Britain and the United States with Japan ended up with a compromise among them.