Dark Humor In Kurt Vonnegut's Slaughter

In Slaughterhouse-Five, Kurt Vonnegut uses dark humor in order to show the harsh reality of war.
After every death in the novel, “So it goes” is said to point out the inevitability of death during both war and life.
This what the Tralfamadorians say when they see someone or something dead.
The phrase does not only apply to humans, but also to animals.
In the book, Billy describes the meat hanging from the ceiling in the slaughterhouse and the Tralfamadorian phrase is said.
Death cannot be stopped because of all the war and destruction that is going on.
The British make the POWs think that everything will be alright.
The British have nice and exciting attitudes towards the POWs. Cinderella music is played the first night at the camp.