In the 21st century, the word chivalry evokes a kind of old-fashioned male respect for women. But during the Middle Ages, the code was established for much grittier reasons.

At a time of routine military violence with massive civilian casualties, chivalry was an effort to set ground rules for knightly behavior. While these rules sometimes dictated generous treatment of the less-fortunate and less-powerful, they were focused mainly on protecting the interests of elites.

The development of chivalry went hand-in-hand with the rise of knights—heavily armored, mounted warriors from elite backgrounds—starting around the time of the Norman conquest of England in 1066. The word chivalry itself comes from the Medieval Latin caballarius, meaning horseman.

In the middle of the 11th century, the knight was not a particularly honorable figure.

“He’s a hired thug,” says Jennifer Goodman Wollock, a professor of medieval studies at Texas A&M University who has written two books about chivalry. “He’s got horses. He’s got armor. He’s like a heavy tank.”

These warriors were commanded by warlords and rewarded with land, or with license to plunder the villages where they did battle, looting, raping and burning as they went.

“In the early Middle Ages, church councils were praying to be delivered from knights,” Wollock says. “What develops as you get into the late 11th, 12th century is a sense that knights have to have a professional code if they’re going to be respected and respectable.”

There was never a firm consensus on what it meant to be a good knight. The most common values found in rules that commanders created for knights revolved around the practical needs of a military force: bravery in battle and loyalty to one’s lord and companions.

“You’ve got all these people who are very prone to violence, heavily armed,” says Kelly Gibson, a medieval historian at the University of Dallas and editor of Vengeance in Medieval Europe. “You’ve got to find some way to get them to get along.”

Still, Wollock argues that chivalry did go well beyond the simple need for a disciplined military. Particularly in romantic literature of the time—some of it written expressly for young noblemen who were being trained for knighthood. Knights were presented as pious, generous and merciful.

“To be a great knight, you ought to have consideration of civilians, for women,” Wollock says. “The greatest knights are inspired by the love of some lady out there and want to impress her and win her love by doing great deeds.”

Of course, it’s hard to know how much of an impression these stories—generally written not by knights themselves but by clergymen or poets—made on young warriors. Richard Kaeuper, a historian at the university of Rochester and author of several books on medieval chivalry, argues that, while knights generally considered themselves honorable and pious, they didn’t necessarily follow religious leaders’ rules.

Kaeuper points to the example of the Fourth Crusade, called by Pope Innocent III in 1202 to seize Jerusalem from its Muslim rulers. Instead, the holy knights ended up sacking the great Christian city of Constantinople.

“The pope said, ‘Don’t do that.’ But what’s he going to do, excommunicate the whole crusade army?” Kaeuper says.

On the flip side, Wollock says, chivalric culture encouraged knights to develop their own sense of morality rather than simply relying on church authorities. That led some of them to question the slaughter of Muslims during the crusades.

Yet even when knights did follow a code of chivalry as they understood it, these ideas about honor and good behavior focused mostly on concern for the noble class that knights were part of, often at the expense of the poor.

“There’s a lot of courtesy—you want to be able to speak well to ladies, defend ladies,” Wollock says. “Ordinary women, shepherdesses, are just rather like for sport.”

Kaeuper says few medieval texts describing chivalry warned against burning or looting towns or raping common women. That style of warfare was still endemic during the Hundred Years’ War of the 14th and 15th centuries, when England and France fought each other, laying waste to the countryside.

“In a way it’s like mafia tactics: ‘You think the king of France can protect you? He can’t. Our king would protect you,’” Kaeuper says.

Kaeuper argues that our current understanding of chivalry as a code of proper masculine behavior, particularly in relation to women, has little to do with real knights in the Middle Ages. Rather, he argues, European neo-romantics in the late 19th century adapted the word to define ideal male behavior.

As for the actual effects of chivalry in the Middle Ages, Gibson says it’s just hard to tell how much a strong focus on honor truly reined in knights’ aggression.

“I think they were pretty destructive,” she says, “even with this code.