During the second world war relations between the United States and Ireland deteriorated to the point that many Irishmen feared that an American invasion of Ireland was imminent. At the same time many people in the United States came to believe that the Irish government of Eamon de Valera was pro-Nazi, This study examines the causes for the deterioration of relations between the two countries and the actual attitudes of David Gray, the United States minister to Ireland, and other American officials toward Irish neutrality. Since there are few secondary works on the subject, the research was undertaken almost entirely among primary sources, personal and diplomatic papers, various American newspapers, and memoirs. Of particular importance were David Gray's personal papers, especially his frequent letters to President Franklin D. Roosevelt.. Copies of some letters, not available among Gray's personal papers at the University of Wyoming, were furnished by the Franklin D. Roosevelt Library, Hyde Park, New York. The study has also made extensive use of the diplomatic papers published by the Department of $tate in the various volumes of the Foreign Relations of the United States. Finally, the author corresponded with more than a dozen of those still living who were personally connected with the wartime relations between the United States and Ireland.