First, let's go over the meaning of chivalry. Chivalry was a medieval code of conduct, especially for knights. It had to do with being an honorable warrior, a pious knight, and a well-mannered gentleman. Honor and nobility were two qualities valued above any other. Through the ages chivalry became more associated with the "well-mannered gentleman" aspect than the former two. Now, we often think of a man courting a beautiful lady, opening doors for her, providing a hanky when needed, playing music, etc. In reality, all three aspects of the chivalric code can be found in Jerusalem Delivered (a work of literature about the crusades).
Of course, the first two aspects of chivalry are inherent in the actual mission of the Crusades which was for the Christians to reclaim the Holy Land (the land of Christ's birth and death and resurrection) from the Turks and other nonbelievers. This involved both being an honorable warrior and a pious knight. Each one was trying to do something special for Christ.
The sacred armies, and the godly knight,
That the great sepulchre of Christ did free,
I sing; much wrought his valor and foresight,
And in that glorious war much suffered he;
In vain 'gainst him did Hell oppose her might,
In vain the Turks and Morians armed be:
His soldiers wild, to brawls and mutinies prest,
Reduced he to peace, so Heaven him blest.
The specifics from Jerusalem Delivered that I would like to focus on have to do with the last aspect of chivalry. Look at what happens when the evil King Aladine orders the statue of Mary to be stolen as a symbol for the anti-Christian side. When the statue mysteriously disappears, King Aladine orders the murder of all Christians. One of the women Christians, Sophronia, gives a false confession, saying that she stole the statue. Her murder is ordered by King Aladine.
Now, here is where the Code of Chivalry comes in:
Olindo, a young knight who always loved Sophronia, gives a false confession as well, saying that he stole the statue and not Sophronia. Unfortunately for both of them, they are both ordered to be burned at the stake. While there, of course in full chivalric form, Sophronia confesses her love for Olindo. They live "happily ever after" when they are saved by Clorinda and escape from the city together, therefore ending a perfect example of chivalry.