The interrelationship of the ideas of apocalypse and millennium is a dominant concern of British Romanticism. The Book of Revelation provides a model of history in which apocalypse is followed by millennium, but in their various ways the major Romantic poets - Blake, Wordsworth, Coleridge, Byron, Keats, and Shelley - question and even at times undermine the possibility of a successful secularization of this model. No matter how confidently the sequence of apocalypse and millennium seems to be affirmed in some of the major works of the period, the issue is always in doubt: the fear that millennium may not ensue emerges as a significant, if often repressed, theme in the great works of the period. Related to it is the tension in Romantic poetry between conflicting models of history itself: history as teleology, developing towards end time and millennium, and history as purposeless cycle. This subject-matter is traced through a selection of works by the major poets, partly through an exposition of their underlying intellectual traditions, and partly through a close examination of the poems themselves.