If I were you I would leave any explanations of any kind out of your first chapter.
I am looking at this as if I were an agent, and an agent has hundreds of mss.'s to read in a years time and has to decide which ones she can sell.After all that's how an agent makes a living.
Your first chapter should be all direct scenes --- direct, pungent, sensual deszcription. Otherwise you will lose your reader (agent).
Did you ever have a friend that said something like 'Oh you can't believe what happened! It was so unfair!' and then proceeds to go into long, long explanations leading up to whatever happened and all you want them to do is just tell you what happened!
So start with the atmosphere of the day, the tattered banners of the 18th North Carolina, the sound of the creek, the sound of Jackson's horse, then the rifleman sighting down his barrel, then the shot, and then the BIG surprise that he misses Jackson entirely.
When you convey information through dialogue, it is called exposition. Exposition is not good. Try to never convey information through dialogue. If you do, consense it into narrative summary.
Chapter 2 then could start with some descrption of the position of the armies.
I know this is a long answere but you have worked very hard on your novel and I am sure it deserves every chance at success.
To avoid any amateurish mistakes, order Making Shapely Fiction by Jerome Stern --- it will explain things like 'tags' and 'narrative summary' etc. It is one of the best books I have ever read on writing and it's funny.
You want your mss. to appear professional and experienced when you send it to an agent.
Hope that helps. How are you over there?
At first, my chapter had no history - just the 18th North Carolina in the dark waiting for the threat to materialize around the bend in the road.
Could it be that the first chapter is just too long. If I just did the missing of Jackson and the orders to Hill to cut the Yankees off at the US Ford... then it might be a faster easier read.
What do you think of putting the terrain and the history leading up to Chancellorsville into a prologue. That way it is optional? If you don't know the history...read it. If you do, do what I do to prologues... pass them by. Introductions too except they usually are the most important part of the book.
Please do not get tired of being an "instructor". I cannot tell you how much I appreciate it.
I’ll bet you enjoyed Zen and the Art of Motorcycle Maintenance.