The tragic endings of these historical figures are recounted: Lucifer, Adam, Samson, Hercules, Nebuchadnezzar, Belshazzar, Zenobia, Pedro of Castile, Peter I of Cyprus, Bernabò Visconti, Ugolino of Pisa, Nero, Holofernes, Antiochus, Alexander the Great, Julius Caesar, and Croesus.
A likely dating for this hypothetical first draft of the text would be the 1370s, shortly after Chaucer returned from a trip to Italy, where he was exposed to Giovanni Boccaccio's Concerning the Falls of Illustrious Men, as well as other works such as the Decameron.
If the Knight were at the capture of Alexandria, then the implication is that he was probably part of the crusade organised by Peter I of Cyprus and that the reader should presume that hearing of the tragedy of his former military commander is what prompts him to interrupt the monk.
[1] The form of tragedy depicted in "The Monk's Tale" is not that argued in Aristotle's Poetics, but rather "the medieval idea that the protagonist is victim rather than hero, raised up and then cast down by the workings of Fortune.
"[2] The text, despite the Monk's insistence upon a strict, homogeneous definition of tragedy, presents as equally tragic a series of tales that diverges considerably in content, tone, and form.