A full Plate armour (the ones knights wore) was developed at the end of 14th century and peaked around 15-16 centuries.
Before that people wore chainmails and partial plates but monglian arrows could penetrate chainmails so they wore plate armours on top of chainmails.
Funny thing is crossbows were banned by the church because it was too cowardly. England used it however. That must made them cowards but who cares when you can win a war.
England was famous for the LONG BOW. The French made heavy use of crossbows, as they required relatively little training to become proficient in. For instance in the battle of Crécy 1346 the French were said to have 20,000 crossbow men. Edward the III army was equipped with long bows.
Full plate armour was still used by cavalry units well into the 17th and 18th century. Like I said only the advent of rifled firearms saw the death of high quality full plate armour. Common infantry abandoned plate mail early, since they relied on mass produced armour of a lower quality.
