Answer:
If I were in this battle, I'd pick the classic Springfield Rifle (Model 1861) because this is the sort of rifle that can turn the tides of battle. For one, the weapon supports the use of Minie balls, which are bullets that fire much faster and farther than standard ammunition. Next, considering it's range of about 400 yards, I wouldn't have to close in on my enemies on that field. Being as far from the enemy as possible is the key to survival because I'm either being attacked from the left flank, or attacking the enemy's left flank. Cornfields have lower visibility as well, so it helps to have a rifle with a 40-inch barrel to swat ears of corn away from blocking my sight.
Explanation: