Halberdiers - in short: an upgraded version of the Spearmen.Unfortunately, due to lack of armor Flagellants are more vulnerable to range attacks.
Aside from that they are identical to normal Spearmen. The only difference is that this variant has shields which are used to block a portion of missile damage (provided that they are facing the side the missiles are coming from). The problem is their lack of shields (which causes them to be vulnerable to missiles), low armor and weak weapon damage - they aren't suited for direct combat against melee-oriented units. Soldiers equipped with swords and shields (the latter allows them to block a portion of missile damage) are used mainly as the starting infantry - their offensive and defensive capabilities won't allow them to keep up with more advanced units that will appear later on.
The Empire has access to the following melee infantry units: