"[1] The play was entered into the Stationers' Register on 14 February 1639, and published in quarto later that year by the bookseller John Waterson; the title page states that it was acted by the King's Men in the Globe Theatre.
In search of a source for Massinger's plot, critics have considered the story of Beatrice Cenci and a passage in Jonson's Catiline that refers to "incest, murders, rapes...incestuous life.
"[3] Scholars have studied The Unnatural Combat for resonances with the events of its era; it has been argued that the play's portrait of its villain Malefort Senior alludes to the sex scandals and witchcraft allegations surrounding George Villiers, 1st Duke of Buckingham.
Nineteenth-century critics tended to condemn The Unnatural Combat for its sensational aspect; but T. S. Eliot praised the play's "deft handling of suspense" and its "theatrical skill.
When Malefort Senior and Junior meet, they converse before the fight – and the son reproaches his father for having committed a "deed of horror" (though he doesn't specify the nature of that horrible action).
Plans are made for the wedding of Beaufort Junior and Theocrine; but their friends note the strange, doting, almost obsessive behavior that Malefort Senior has begun to show toward his daughter.
One is a group of Theocrine's servants that includes her Usher, waiting women, and especially her Page; the other, and the more important one, is the figure of Belgarde, a cashiered captain who has to struggle for survival, cadging free meals wherever he can.
Belgarde also supplies social commentary on the fates of soldiers and sailors who are no longer needed by society (relevant, perhaps, in the aftermath of the Cadiz campaign).