SOURCE: Introduction to King John, in Narrative and Dramatic Sources of Shakespeare, Vol. IV, edited by Geoffrey Bullough, Routledge and Kegan Paul, 1962, pp. 1-24.

In the following excerpt, Bullough argues that The Troublesome Reign was Shakespeare's source for King John and presents a comparison of the two plays so that readers can decide for themselves.

. . . The year 1591 saw the publication of an anonymous play, The Troublesome Raigne of John King of England, which was printed in two parts,¹ quite unnecessarily, for it was obviously written as one piece. The two parts were printed together in 1611 by Valentine Simmes for John Helme, as 'Written by W.Sh.'. A third edition in 1622, printed by Aug. Mathewes for Thomas Dewe, asserted that the play was 'Written by W. Shakespeare'. It has often been suggested since that the play was Shakespeare's in whole or in part. Pope attributed it to Rowley...