Chivalry

Chivalry is a unique campaign mechanic for Bretonnia, introduced in Total War: Warhammer.

Description
Chivalry is shared across your entire faction. It can be gained from winning battles, with greater victories (eg: Heroic victory vs Pyrrhic victory) granting more chivalry. Chivalry can be lost when performing unchivalrous actions such as sacking settlements and raiding provinces. Your Lord's character traits also have a large impact on your faction's overall Chivalry level.

When your faction reaches certain levels of chivalry, they will gain access to The Green Knight, a unique hero unit who lasts a limited number of turns. However this can only be done a maximum of 4 times in Total War: Warhammer, but as of the Doomsayers Update in Total War: Warhammer II, the Green Knight can be summoned an unlimited number of times when at max chivalry.

Strategy
One strategy with Bretonnia to gather Chivalry quickly is to spam paladins, lords and prophettesses. Each gives you +5 to +10 Chivalry. If you have the economy, you can get an infinite supply of paladin to boost your chivalry score to the roof!