Garrett holds a BS in International and Strategic History from the U.S. Military Academy and an MA in Military History from Austin Peay State University. Broadly, he studies twentieth-century American military history, especially the U.S. Army's experience between 1890 and the 1953. Garrett's other areas of interest include American history, Russian history, and their interactions. Garrett's research concentrates on the creation of martial physical cultures, defined as constellations of ideas and practices dealing with the improvement of human bodies, minds, and spirits through physical activity and disciplinary activities. His research informs perceptions of war, battle, and citizenship.