Chivalry 2's combat system is in-depth and made up of numerous systems, and one of these is parrying. Parrying is when a player matches the attack of an opponent to deflect the blow.
Doing so requires excellent timing and for you to read the opponent's movements. That said, you can parry by watching the opponent's hands and seeing which direction they are about to attack in.
For example, if it's a sword swing to the right, you will then need to do a right swing to parry that incoming attack by hitting the right mouse button.
You can also launch a counterattack right after blocking your foe's attack. To do this, you must hit an attack button immediately after deflecting an attack. Another thing to remember is to not hold down the block button for too long, as it will drain stamina, and if your enemies drain yours completely, you can be disarmed.
So the best thing to do is to counterattack and block in quick succession, do not let your foe have enough time to attack you again, so stay on the offensive.
We also recommend focusing on 1v1 opponents when you can, because fighting and parrying multiple attackers is tricky business. Try staying with teammates and look for an opening to attack to avoid multiple attackers.
For more on Chivalry, check out Are the Chivalry 2 servers down? Here’s how to check server status and Will Chivalry 2 have a campaign or single-player mode?.