In The Red Badge of Courage, how had the young soldier, Henry Fleming, imagined war?

Before he leaves home, Henry as a very romantic idea about war. He envisions himself coming home as a hero and having all the girls admire him. His mother is more realistic saying,""'Yer jest one little feller amongst a hull lot of others, and yeh've got to keep quiet an' do what they tell yeh. I know how you are, Henry.'" However, she knows Henry must learn about war for himself. Henry never thought about how cold, dirty and sometimes tedious war can be, especially when his regiment is waiting in training camp. As he begins to think about his real situation, he begins to be afraid that he might run when actually called to fight.