The Stanzaic Morte Arthur is an anonymous 14th-century Middle English poem in 3,969 lines, about the adulterous affair between Lancelot and Guinevere, and Lancelot's tragic dissension with King Arthur. The poem is usually called the Stanzaic Morte Arthur or Stanzaic Morte (formerly also the Harleian Morte Arthur) to distinguish it from another Middle English poem, the Alliterative Morte Arthure. It exercised enough influence on Thomas Malory's Le Morte d'Arthur to have, in the words of one recent scholar, "played a decisive though largely unacknowledged role in the way succeeding generations have read the Arthurian legend".