What happened to the knights after the middle Ages?

At the battle of Crecy, arrows from English longbows penetrated the metal of the armor used by knights. (In Eastern Europe full body armor proved ineffective against Mongol recurve bows.) After that the job of knight as a warrior was replaced by that of a cavalryman. Cavalrymen would carry shields but would no longer carry full body armor.

In England, the position of knight became an honorary rank.