This dissertation lays the foundation for a comprehensive picture of World War I and Japan. While European and American scholars have long studied and recognized the wide-ranging effects of the war on the domestic and foreign affairs of their respective countries, no comparable studies have been made of Japan by any historian, Japanese or foreign. As the initial phase of this project, the letters, diaries, and memoranda of Japan's policy-making elite are analyzed in an effort to go beyond the compartmentalization of domestic politics and foreign affairs that has characterized much of the scholarship on Taisho era Japan (1912-1926). In the process, the study develops a clear outline of foreign policy decision-making during the Great War.

The dissertation presents the making of continental policy in terms of the struggle for power among Japan's elder statesmen, peers, armed forces, and political parties. In 1914, a consensual agreement upon the promotion of continental expansion provided a unifying element to the domestic struggle for power. By 1917, however, President Woodrow Wilson's pronouncements against German militarism to make the world "safe for democracy" exacerbated the tensions between advocates of parliamentary politics and their adversaries and created disagreements over how best to promote continentalism. By 1919, policy-makers divided over the wisdom of continental expansion itself and over the implications of membership in the League of Nations for the scope and nature of political and social reform at home.

The dissipation of a consensus on continentalism marked the beginning of a decade of military retrenchment and political reform commonly known as "Taisho democracy." But Japan's military-bureaucratic elite did not cease their resistance to encroachments on their political power, nor did they abandon their commitment to continental expansionism. Their devotion to empire, autocracy, and armed might persisted throughout the 1920s and culminated in war against China and the United States in the 1930s and 40s. By focusing upon the pursuit of empire during World War I, the present study relates the impact of the Great War to Japan's drive for hegemony in the Second World War.