My question says:

How is naturalism used in "The Red Badge of Courage" and come up with three quotes.

First of all, can someone explain what naturalism really is?

2 answers

Naturalism is trying to understand the world as a process of natural causes, not relying on the supernatural to explain the process. Love of God, Country, making the world safe for democracy, and Mom's apple pie are not valid explainations in naturalism. Logic and observations play a leading role in naturalism.

Good question, and it offers some insight to the Red Badge.
http://en.wikipedia.org/wiki/Naturalism_(literature)
This is a really good definition.

Naturalism is reflected in how the author decides to portray settings, characters, actions, thoughts, etc.
Since RBOC doesn't glorify war, that's the cornerstone of naturalism in that particular work, it seems to me!

=)