When I was a schoolboy, Robert Browning's "My Last Duchess" as a standard item in the English curriculum. It had many features calculated to excite the minds of the young, foremost among them a ruthless, egotistical tyrant of such power and vanity that he could openly admit to having ordered the execution of his own wife for the "crime" of being too pleasant to others. Critics have not been of one mind about the meaning of the poem, or even the psychology of its ducal speaker. Robert Langbaum, who regards himself as something of an authority on the poem, writes, "It is because the duke's motive for telling the story is inadequate, and because the situation is never resolved in that the utterance is not quite directed to the auditor and does not accomplish anything, that we look for a resolution in the duke's life outside the poem" [my italics, indicating where I think Langbaum mistaken]. William Harmon declares, "The duke is dignified and cagey but not quite cagey enough. Some inner compulsion, probably an overwhelming sense of guilt, has compelled him to return to the scene and situation of his crime and to confess." This seems to me equally mistaken.
Browning's duke is based on Alfonso d'Este, duke of Ferrara, whose first wife died under mysterious circumstances only three years after her marriage. Like historical novelists of our day, Browning allowed himself some latitude in creating his psychological portrait. But he was a keen student of history, and he would have known all about the moral vagaries of Italian Renaissance princes, a topic Shakespeare himself was acquainted with. Regarding the d'Este family, Jacob Burkhardt writes:
Within the palace frightful deeds were perpetrated; a princess was beheaded (1425) for alleged adultery with a stepson; legiti ...