This thesis works with the discourse historical approach (DHA) as the primary framework for the diachronic analysis of a corpus of commemorative speeches by United States presidents at the annual Memorial Day event. The study integrates micro-text and narrative analysis with study of parallel co-texts (especially the Gettysburg address), and seeks to align these with the context provided by social, cultural and historical rituals. I have sought to demonstrate the means by which speakers seek to use Memorial Day in their politolinguistic repertoire to secure a self-serving, legitimizing 'common ground' that elevates the normative value of war in preference to alternative peace-oriented discourses. In addition to analysis of legitimizing strategies, I focus on aesthetic or poetic rhetorical devices typical in the Memorial Day text," and demonstrate their important function in reinforcing and maintaining collective attitudes to memory and history. American Memorial Day thus serves as a case study for the exploration of discourses that perpetuate and legitimize war as activity that is necessary and integral to historical 'progress'.