Why is Holden opposed to war?

Holden calls Carl Luce, a friend from the Whooton School who goes to Columbia, and plans to meet him that night. He then goes to the movies and is annoyed when a woman beside him becomes too emotional. The movie is a war film, which makes Holden think about D.B.’s experience in the war. D.B. hated the army, but had Holden read A Farewell to Arms, which in Holden’s view celebrates soldiers. Holden thinks that if there is a war, he is glad that the atomic bomb has been invented, for he would volunteer to sit right on top of it.