You can join the battle as soon as you open Chivalry 2.

Also, don’t be alarmed by the frequent use of the battlecry key (C on your keyboard, if you were wondering). As for this multiplayer slasher-game’s historical accuracy… well, don’t be surprised when you see the occasional armless soldier running around on the battlefield. Looking for Chivalry 2 tips? Just like its predecessor, Chivalry 2 gives you the full medieval combat experience: knights, siege engines, and a whole lot of gore.