H ISTORICAL WRITING about American rejection of the Versailles Treaty has too often reflected the inability of historians to resist the temptation to portray the events of 1919-1920 as a classic struggle between the executive and the legislative branches, between a stubborn Democratic President and a waspish Republican Senate, or-even more narrowly-as a personal duel between Woodrow Wilson and Henry Cabot Lodge. Although such interpretations do explain a great deal, they tend to ignore the extraordinary public furor over the treaty. American politicians do not operate in a vacuum. In the United States, as in all democracies, legislators are responsive to public opinion. Traditionally, pressure groups have most effectively brought such opinion to bear on congressmen; and throughout American history, minorities have been better organized than majorities to exert this pressure.' Minority opinion has seldom been more militant or influential than it was in 1919, when a cluster of ethnic groups became embittered by the frustration of their parent nationalities at the peace conference. Among these immigrant peoples none became more cynical, more militant, or more influential politically than the Irish. Paradoxically, however, just a few months before the Senate began debate on the treaty, it looked as if the Irish would join ranks with those groups most fervently supporting the Wilsonian peace. Significant Irish-American opposition to the Versailles Treaty originated in the spring of 1919. Agitation for Ireland's freedom had been characteristic of Irish politics in America since the era of the French Revolution, and Celtic optimism and exuberance ran especially high in the weeks preceding the opening of the peace conference at Paris. Victory in the struggle for Irish independence ap