This thesis is both a literary history of the military science fiction (military SF) subgenre and a cultural history of the United States of America during the twentieth and early-twenty-first centuries. This thesis academically rehabilitates a neglected literary subgenre, and utilises it to prove the efficacy of using literary texts, specifically science fiction (SF) texts, in the study of cultural history. It expands both the sources and methods of interpretation open to cultural historians. Employing the military SF subgenre as its archive, it examines the military SF narratives’ engagement – through extrapolation, metaphor and allegory, as well as didacticism – with their historical-cultural contexts and those contexts’ popular rhetorics, adopting methodologies from cultural history, the history of ideas, and the literary New Historicism. In addition to looking at period-specific themes – ranging from the emergence of the military-industrial complex and consensus anticommunism during the 1950s, through soldier alienation and the ‘cult of the mercenary’ during the Vietnam and post-Vietnam era of the 1970s and 1980s, to the renewed American Exceptionalism and military-civilian divide of the 2000s – this thesis focuses on American attitudes towards militarism and militarisation. The concept of militarism also provides a foundational division in the subgenre, between the two ‘streams’ of militaristic military SF and antimilitaristic military SF. This thesis, however, shows that the subgenre has primarily been sympathetic to militaristic and right-wing rhetorics, support for which has become increasingly strident in modern military SF.