This is actually a very tricky question, in part because chivalry itself is such a complex and debated topic. The chivalric code evolved over the course of the Middle Ages; the emphasis on courtly manners, for instance, was a relatively late development. Furthermore, certain values or practices associated with chivalry arguably come into conflict with one another. An obvious example is the implicit tension between courtly love—a romantic (though ideally unconsummated) devotion to an often married woman—and Christian views on fidelity and chastity. All in all, the idea of chivalry as a consistent code of honorable conduct was probably more prevalent at the time Rostand was writing (the late nineteenth century) than it ever was during the Middle Ages.

Then, of course, there's the question of whether Cyrano himself is a chivalric figure or a subversion of one. Although he displays many qualities associated with chivalry—bravery, loyalty, personal integrity, etc.—he also departs from the tradition in some notable ways. It's not simply that the heroes of (for example) Arthurian legend are conventionally handsome, but rather that they do not for the most part struggle with the extreme self-doubt and depression that Cyrano's fixation on his nose symbolizes. For this reason, it's significant that Cyrano tells Christian that "Blended, [they] make a hero of romance" (2.10); neither he nor Christian quite embodies that hero, but they compensate for one another's flaws in such a way that they approximate a romantic hero when taken together.

With all that said, here are a few examples of Cyrano behaving in what could be considered a chivalric manner.

1. In act 1, scene 4, Cyrano tosses a purse full of coins to the crowd as recompense for the performance he has interrupted. Particularly given his later admission that the purse was all he had to live on for the coming month, the act demonstrates chivalrous largesse. Likewise, in act 1, scene 7, Cyrano single-handedly fights off a hundred men sent to kill his friend Lignière, demonstrating both bravery and a commitment to defend the weak against injustice. Interestingly, Cyrano himself is quite aware of the literary or aesthetic connotations of these actions, and he arguably does them as much to project an image of himself as a romantic hero as he does to pursue virtue for its own sake. For instance, when a friend decries giving away his money as "folly," Cyrano responds, "But what a graceful action! Think!" (1.4).

2. In agreeing to help Christian pursue Roxanne, Cyrano arguably embodies the ideal of courtly love. Cyrano holds out little hope that Roxanne could ever return his own affections and—knowing that she loves Christian—helps Christian court her so that both he and Roxanne can be happy. The example is complicated, however, by both the deception involved in the scheme and by the fact that Cyrano's motives may not be entirely pure; in fact, Christian is initially reluctant to agree to the plan precisely because he notices Cyrano's excitement—that is, his eagerness to be able to pursue Roxanne in some fashion.

3. Perhaps most poignantly, when Christian is dying in act 4, scene 10, Cyrano lies to him, telling him that he has confessed the truth about the love letters to Roxanne and that it is indeed Christian she loves. He maintains his silence on the topic until his own death fourteen years later. Although this dishonesty appears to contradict the chivalric emphasis on integrity (as well as the value Cyrano personally places on honesty), this in some sense makes Cyrano's sacrifice all the more significant; he not only sacrifices any hope of a relationship with Roxanne but also his own moral code out of loyalty to Christian. One could therefore argue that by the time of his death, Cyrano has come to embody chivalrous virtues in a less self-conscious and thus more authentic way. In particular, the way he rails against "Falsehood," "Treachery," and "Compromise" as his "old enemies" suggests that he's aware that the persona of the romantic hero he has worn for years was, to some extent, a false one but that he nevertheless yearns to live up to the ideals he has spent his life trying to project.

Of his main character Edmond Rostand observed that he has "panache": "not greatness ... but something which ... stirs above it ... the spirit of gallantry.' Certainly, Cyrano de Bergerac captures chivalry and wit in every act. But, there are three salient acts of chivalry in this drama:

1. In Act II, although Cyrano himself is deeply in love with his cousin Roxane, he agrees to watch over Christian when Roxane comes to him with her loving plea for the soldier of the Gascony guards with whom she is infatuated. And, although Cyrano believes at first that she thinks of him, but is disappointed when she calls the man "handsome." Nonetheless, he agrees ironically with Roxane's statement that she and Cyrano are such good friends that he can help her obtain the man's love,

There's nothing finer than

Friendship.

2. Also in Act II, despite his being desperate in love with Roxane himself and despite Christian's insults about his nose, Cyrano gallantly assists Christian in his love affair by helping him with a letter to the pretty maiden. As Christian frets about his skills with love poetry, Cyrano suggests facetiously, but yet with some gallantry, that Christian borrow his talents,

Well, why not borrow it!

And, in return, I'll borrow your good looks.

There's promising albegra here: you plus I

Equal one hero of the story books.

3. Then, in the final act, Act V, as he is dying, Cyrano yet retains his staunch devotion to his code of honor. Covering his fatal head wound with a hat to disguise the bandage, Cyrano acts as though nothing is different when Roxane visits him; he recites his daily "gazette" of satiric news.When Roxane asks about his wounds, he makes light of them; then, she replies,

We all of us 

Have our old wounds

and she pulls a yellowed letter, bloodstained, from her bosom. Cyrano reminds her that she has promised to read Christian's dying letter to him. As Cyrano, then, reads the letter, night approaches. Yet, he is still able to "read" this barely legible letter. So, Roxane deduces that it has been Cyrano all along with whom she has been in love; nevertheless, Cyrano protests, "Upon my honour....I never loved you."