This dissertation identifies in British Romanticism a poetics of heightened attention inseparable from wartime vigilance. This poetics criticizes the political alarmism of the Romantic period, yet also maintains an unexpected proximity to the forms of apprehension and vulnerability prompted by war, as well as to the uncertain epistemology and phenomenology of wartime experience. Instead of resisting the militarization of attention in the 1790s with an aesthetics of distraction, the Romantic texts studied here propose an alternative form of attention, one more receptive than defensive, aiming to decouple alarm from fear. Aesthetic experience emerges as a mode of keeping watch that, while indebted to wartime concerns about security and susceptibility, refuses to predetermine the object of its watch. Attention thus designates a critical site at which history, ethics, and aesthetics intersect. The first chapter investigates Wordsworth's observation that new perceptions arrive only when the "organs of attention" relax; it finds in The Prelude the promise that both poetic and historical perceptions may be produced through the rhythms of attention built into verse form. The second chapter considers the relation between sound, war, and alarmism in Cowper's "The Needless Alarm" and Coleridge's "Fears in Solitude," and suggests that both poems resist alarmism by widening the gap between sound and signification, while distinguishing poetic from political uses of "empty sounds." In the third chapter, I read Charlotte Smith's "Beachy Head" as a response to the characterization of France as England's "natural enemy." Attuned to the intersections of national security, wartime perception, and nature's history, Smith refigures the more militant coastal prospect poem by turning to the geological history of the coast; this view reveals instead a natural topography that linked England to France, rather than dividing the two nations in a "natural" enmity. The fourth chapter suggests that Godwin's Caleb Williams and Austen's Northanger Abbey understand alarm as a form of subjection. It explores both novelists' use of the Gothic genre to ask how alarm functions as a pretext for the expansion of power. The coda finds in the twenty first century an afterlife for Romanticism's wartime poetics of attention.