Early in the novel, Vonnegut (as the narrator) comments on the machines of war. He says that he has raised his sons not to glorify these machines and to feel repulsion for the people who do think that these machines are necessary.
Later in the novel, Billy Pilgrim watches a war film in reverse. This section shows a clear emphasis on the mechanical and industrial nature of war.
"The bombers opened their bomb bay doors, exerted a miraculous magnetism which shrunk the fires, gathered them into cylindrical steel containers, and lifted the containers into the bellies of the planes.… The steel cylinders were taken from the racks and shipped back to the United States of America, where factories were operating night and day, dismantling the cylinders, separating the dangerous contents into minerals … [which] were then shipped to specialists in remote areas. It was their business to put them into the ground, to hide them cleverly, so they would never hurt anybody ever again."
Billy is presented in contrast to the machines of war in that he carries no gun and the only time he is not walking during his time in Germany, he rides in a horse-drawn carriage.