Leland was a staunch patriot, and believed firmly in the historical veracity of King Arthur. He therefore took offence when the Italian scholar Polydore Vergil cast doubts on certain elements in the Arthurian legend in his "Anglica Historia" (published in 1534). Leland's first response was an unpublished tract, written perhaps in 1536, the "Codrus sive Laus et Defensio Gallofridi Arturii contra Polydorum Vergilium". ("Codrus", a pseudonym for Vergil, was a type-name drawn from Juvenal for a wretched and dreary hack-poet.) He followed this with a longer published work, the "Assertio inclytissimi Arturii regis Britannia" (1544). In both texts, Leland drew on a wide range of literary, etymological, archaeological and oral sources to defend the historicity of Arthur. Although his central belief was flawed, his work preserved much evidence for the Arthurian tradition that might otherwise have been lost.