Hi I'm new to this subreddit, so I hope that i'm not disrupting a "decorum" or rules with my question.
I have always wondered how historians, especially in the military history field, determine the outcome if a commander made a different choice or if a mission happened differently.
Do historians use diaries of opposing ocmmanders, calculation of troop movement?
How would the two armies react to new situations?
It's like the "what if" questions. You cannot answer them because there are too many things that can happen. Sure you can assume some stuff but if you think of it, everything could possibly happen.