A note to the "Incantation" (Manfred, act i. sc. 1, lines 192-261), which was begun in July and published together with the Prisoner of Chillon, December 5, 1816, records the existence of "an unfinished Witch Drama" (First Edition, p. 46); but, apart from this, the first announcement of his new work is contained in a letter to Murray, dated Venice, February 15, 1817 (Letters, 1900, iv. 52). "I forgot," he writes, "to mention to you that a kind of Poem in dialogue (in blank verse) or drama ... begun last summer in Switzerland, is finished; it is in three acts; but of a very wild, metaphysical, and inexplicable kind." The letter is imperfect, but some pages of "extracts" which were forwarded under the same cover have been preserved. Ten days later (February 25) he reverts to these "extracts," and on February 28 he despatches a fair copy of the first act. On March 9 he remits the third and final act of his "dramatic poem" (a definition adopted as a second title), but under reserve as to publication, and with a strict injunction to Murray "to submit it to Mr. G[ifford] and to whomsoever you please besides." It is certain that this third act was written at Venice (Letter to Murray, April 14), and it may be taken for granted that the composition of the first two acts belongs to the tour in the Bernese Alps (September 17-29), or to the last days at Diodati (September 30 to October 5, 1816), when the estro (see Letter to Murray, January 2, 1817) was upon him, when his "Passions slept," and, in spite of all that had come and gone and could not go, his spirit was uplifted by the "majesty and the power and the glory" of Nature.

Gifford's verdict on the first act was that it was "wonderfully poetical" and "merited publication," but, as Byron had foreseen, he did not "by any means like" the third act. It was, as its author admitted (Letter to Murray, April 14) "damnably bad," and savoured of the "dregs of a fever," for which the Carnival (Letter to Murray, February 28) or, more probably, the climate and insanitary "palaces" of Venice were responsible. Some weeks went by before there was either leisure or inclination for the task of correction, but at Rome the estro returned in full force, and on May 5 a "new third act of Manfred—the greater part rewritten," was sent by post to England. Manfred, a Dramatic Poem, was published June 16, 1817.