How could Morte d'Arthur be considered a "civilizing" force in the medieval period?

A major theme throughout the text, chivalry defines the code of ethics that the Knights of the Round Table must uphold. This is considered a major "civilizing" force behind the medieval period. King Arthur cements the importance of chivalry within the fellowship of the Round Table by asking his knights to renew their vows of knighthood at Pentecost each year, promising to protect women and to flee from treason and murder. Most of the main characters, including King Arthur, Launcelot, and Gawaine, uphold their promises of chivalry; however, they, like many of the other characters, break their vows on various occasions. For instance Arthur kills the sorceress Annowre; Launcelot fights and kills other Knights of the Round Table; and Gawaine encourages Arthur to go to war with Launcelot. Chivalry is as much an ideal for knights to strive for than an easily realized virtue.