History, and literary history, is confusing. But what's the point of talking about Romantic or 18th century literature if you have no idea how it fits into a timeline? Okay. So, here's a nice, simple timeline.
1. Anglo Saxon poetry: like Beowulf or "The Dream of the Rood." This is written in the early, Germanic, form of English and is either epic and heroic (like Beowulf) or devotional (religious). There are also folk poems: wedding songs, drinking songs, erotic poetry etc.
2. 14th century poetry: the High Middle Ages. This is written in a transitional form of English, with much influence from the Norman Conquest of England (i.e. words from French). Chaucer's Canterbury Tales are the prime example, and these are probably commonly-told stories: some baudy, some religious, some with a lesson. The 14th century was a somewhat gloomy time, and much of its literature has a dark, theological cast. Other notables: John Gower, William Langland.
3. The Renaissance (15th & 16th Cs). Here are some cliches: beginning of the modern age due to the rise of the middle class; growing technology including the printing press; power of the church and new wealthy class rivals the power of the monarchy. Renaissance writers were backward-looking, obsessed with the classics (meaning ancient Greek and Roman classics). They were also "magpies" - meaning that they borrowed a lot from everywhere. Shakespeare's work is a collage of information from growing fields like science, history, even anthropology. Colonialism was almost beginning. A lot of poetry is theological (Milton, Spencer), but Shakespeare was strangely and determinedly secular. This is the preeminent period for England in world literature; England was undoubtedly the leader at this time.
4. 17th century devotional poetry: The early 1600s were a mix of free-thinking tendencies and a kind of harsh religiosity. It is best known for the witty, compressed work of the "metaphysical" poets of this time: Donne, Herbert, Crashaw, Carew, Vaughn, etc. They used remarkably complex images that mixed secular with religious ideas.
5. The Restoration: In the mid-1600s, England had a revolution, the "Puritan Revolution," which led to the overthrow of the monarchy and the institution of a republican (representative) government. But it didn't last. So, around 1660, king Charles II was restored to the throne, and a period of celebration followed: "the Restoration." Poets of this time were conservative (pro-monarchy, at least on the surface) and satirical (making fun of classic works or of the aristocracy). Examples: Dryden, Pope, Marvell.
6. 18th century literature. So, by now the "modern" world is well-established. The novel, beginning with Defoe (Robinson Crusoe; Moll Flanders) and Richardson (Pamela) became a popular form. Essays were popular. Poetry? There was Samuel Johnson, Jonathan Swift, late Marvell. This was the post-Enlightenment, an extremely rational time in literature & philosophy.
7. Romanticism. (1780s-1830s, approx.). In the wake of the French Revolution (1789-90s), a new political world was opening up. The English and German romantics looked backward to mythic and pagan ideas, resuscitating them. They rejected the rationality of previous writers and embraced dream, myth, mystery, inebriation, instinct... They liked to rework folk tales and heroic tales. They were tree-huggers who thought all wisdom was contained in nature.
8. Victorian era. Somewhat dark and preoccupied with gothic concerns, this was the age of Freud and the polite novelists: Henry James, Edith Wharton (American), George Eliot, Jane Austen, Thackeray. An infinitely more restrained time in reaction to the freethinking Romantics, the Victorian age was not a great flowering of poetic genius. Science was booming. The novel was enjoying probably its best period ever. Who had time for poetry?
9. The Moderns: This is where America comes into its own as American-born figures like T.S. Eliot and Ezra Pound brought the poem back to life. They rejected both Romanticism and the 18th century or Restoration rationality, wishing to go back to a time when poetry mixed emotion with braininess. Avant-garde modernism followed.