You can read regimental histories, campaign analysis, letters, diaries, and the Official Records till the end of time, but there's a conspicuous gap in your studies if you've never read Mark Twain's account of his Civil War service. The good news is that it's only a click away, online here, and other places. The passage below gives you the flavor of the story. Here, the young volunteer and his fellow recruits, content in camp, learn that the enemy is headed their way:
For a time, life was idly delicious. It was perfect. There was no war to mar it. Then came some farmers with an alarm one day. They said it was rumoured that the enemy were advancing in our direction from over Hyde's prairie. The result was a sharp stir among us and general consternation. It was a rude awakening from our pleasant trance. The rumour was but a rumour, nothing definite about it, so in the confusion we did not know which way to retreat. Lyman was not for retreating at all in these uncertain circumstances but he found that if he tried to maintain that attitude he would fare badly, for the command were in no humour to put up with insubordination. SO he yielded the point and called a council of war, to consist of himself and three other officers, but the privates made such a fuss about being left out we had to allow them to remain, for they were already present and doing most of the talking too. The question was, which way to retreat; but all were so flurried that nobody even seemed to have even a guess to offer. Except Lyman. He explained in a few calm words, that inasmuch as the enemy were approaching from over Hyde's prairie our course was simple. All we had to do was not retreat toward him, another direction would suit our purposes perfectly. Everybody saw in a moment how true this was and how wise, so Lyman got a great many compliments. It was now decided that we should fall back on Mason's farm.