i believe you got mixed up there with the "romans"
what you meant was the Holy Roman Empire which was a VERY important entity in this time period. it can easilly get confusing because the Holy Roman Empire actually had NOTHING to do wiht the Romans.
it was actually a group of hundreds on mostly german governments.
some of the more powerful ones became "electorates" these "electorates" picked who would have the honour becoming the Holy Roman Emperor.
some of the most important nations in the empire were:
Venice,Austria,Prussia,Saxony,Brandenburg,Mainz,Palatinate,Bohemia,Bavaria,Munster,Burgundy (the list is truly endless, there were hundreds of principalities, duchies, counties, Free Imperial Cities, as well as other domains.)
so you see. there special unit should be a special type of crusader (the Holy Roman Empire had a Religious side that caused things to get a bit messy due to the pope and debate's over authority.)
still you should add this cause this empire is important