In the later poetry and critical writing of Geoffrey Hill, W. B. Yeats has come to cast an ever more ‘majestic Shade’ and in Liber Illustrium Virorum is styled as Hill’s ‘seamark’, a beacon that is as much a warning as it is a touchstone. Yeats’s political (and indeed apolitical) dubieties of the 1930s in contrast to what Hill sees as some of his finest work in Last Poems and Two Plays of 1939 serve as an enabling dilemma, energizing and tempering Hill’s most recent poetry. ‘Seamark’ is an allusion to Shakespeare’s Coriolanus, and Hill repeatedly associates the antimonies of that play’s ‘mode’ or polyphonic style in contrast to the reductive politics of its individual characters as analogous to the ‘grandiose confusions’ in Yeats between a masterful, politically sophisticated style and lapses into fascist screed or apolitical posturing. This article examines Hill’s reception of Coriolanus as a play crucial for understanding twentieth century poetics, particularly in the wake of modernism and its ‘twin betrayals’: political aesthetics and apolitical aesthetics. The article excavates the imaginative grounds of Hill’s link of Coriolanus to the work of W. B. Yeats, detailing the latter’s sustained, underexplored fascination with the play.