When two units of, say, infantry were to engage in battle, either by charging at each other or just one side attacking the other, what happened?
Was it like in Total War games where one formation smashes into the other and the front ranks fight it out, replace losses with men deeper in the formation and keep at it until one side gets routed or decides to disengage? Did they stop short of smashing into each other and try to intimidate one another with a few men running out of the formation to poke at the enemy or engage in duels?
What I'm basically asking is if soldier could be trained to charge into another line of men pointing sharp objects at them, or if they would balk at the idea and refuse to do it. Is there an authentic visual representation of how battles were fought?
This doesn't answer your question but it does give you some perspective regarding conflicts when it involves men who are not directly connected to a conflict.
I'm going to talk about the English civil war(s) for a moment.
During this time men found themselves pledging their swords to their lord. The lord picked a side and sent these men to fight. These men were fighting other Englishmen in a conflict so complicated that most if not all of them (except the Scott's and Irish) were uninterested. England at he time did not have a standing army so these men were mostly untrained and unpaid.
During this time pikemen on both sides came up with the idea (the idea might actually be a lot older than this war) to stand at a pike's length and soar with each other. Basically, they would yell and scream and push each other's pike out of the way. From a distance, it sounded and looked like both lines were fighting.
When there are two uninterested men on two sides of a battle neither want to die for a cause that don't believe in or understand. Now this is a specific instance. There are reasons for men to charge into a line of other men who want to kill you. The Romans did it for honor but English in this time had very little interest in honor, dying, or parliament.