Why did knights become a distinct group, and when did they decline?
The feudal structure of France imposed a dual role on the peasants. They provided services to the lords and also rendered military service at times of battles. However, from the 9th century, a need emerged for more skilled soldiers, as localised wars became more frequent. Thus, specially trained armed warriors or knights emerged as an important component of the societal setup. The knights had complete loyalty to the lords and they provided total support in the wars. In return for their services, the knights were guaranteed huge areas of lands or fiefs.
The practice of knighthood declined from the 12th century when technological advancement brought in new kinds of weapons like arbalest and crossbows. These weapons could be used by any foot soldier and could kill any highly trained knight in one shot. The final blow to this system was the use of gunpowder in battles. Knighthood could not stand before the changed pattern of the medieval warfare; therefore, the class of knights declined.