A few days back, I brought up Homer’s The Iliad as a possible source for Shakespeare’s Troilus and Cressida. That works for the Trojan War aspects of the play. But as I mentioned, there’s no link in the poem between Troilus (who’s mentioned in the poem only as a dead son) and Cressida (provided she is even the Chryseis of the poem).
So where did Shakespeare
steal, uh, get the love story?
The broad strokes go back as far as the twelfth century, in a work by Benoît de Sainte-Maure called Le Roman de Troie (“The Romance of Troy”). An epic poem, it retells the Trojan War with an emphasis of the protagonists being more than warriors, but lovers, too. Perfect for a courtly love-lovin’ court audience. It introduces Troilus as a lover of the Cressida character–here called Briseis–who is traded for by her father, the Trojan priest Calchas, who has defected to the Greeks. Once Cressida is reunited with her father through a ransoming of a captured Trojan soldier, she is wooed by the Greek Diomedes.
Le Roman de Troie was translated into the Latin by Guido delle Colonne, and it was probably this work called Historia destructionis Troiae (which turned Briseis into Criseida), that was read by the early fourteenth-century Italian poet Giovanni Boccaccio. And the love story would then appear in his Il Filostrato, which introduces the character Pandarus. In this version, Diomedes seduces Criseida; when Troilo learns this, he attempts to exact revenge. Though he never kills Diomedes, Troilus slaughters many Greeks… until he’s killed by Achilles.
That version was then picked up in the late fourteenth century by Geoffrey Chaucer, who reworked it in his Troilus and Criseyde. As you can see, Cressida gets another name change (and Troilus is back from being Troilo). And this is probably the version that Shakespeare knew.
There was another version of the story from between Chaucer and Shakespeare, a fifteenth-century poem by Robert Henryson called The Testament of Cresseid. It tells a kind of “what happened to Cresseid afterwords” story. But as Troilus and Cressida doesn’t include this portion of the story, it probably wasn’t an influence.