This article examines the World War I service of the University of Michigan historian Ulrich Bonnell Phillips (1877–1934). Phillips worked first with black recruits as a volunteer officer for the Young Men's Christian Association at Camp Gordon, Georgia, and later as a U.S. Army Military Intelligence officer in Washington, DC. In these years, Phillips ranked as America's foremost authority on the antebellum South generally and of African American slavery in particular. In 1918 he published his landmarkAmerican Negro Slavery. While on leave from Ann Arbor, Phillips taught English and French, planned educational and recreational programs, and supervised the management and construction of buildings at Camp Gordon's segregated facilities. Phillips's daily interactions with black troops in the cantonment reaffirmed—at least as he saw it—his conclusions that North American slavery had been a relatively benign institution, his belief in the virtues of plantation paternalism and in the management of subject peoples by educated whites, and his attitude that contemporary race relations were generally harmonious. Phillips's observations of African American recruits validated his conviction that blacks benefited most from white-run, regimented organizations and strengthened his belief in economic assimilation and social segregation. His military intelligence work confirmed Phillips's overall commitment to conservative change, whether in foreign or race relations.