Kurt Vonnegut Jr. had a menial career in writing by the time he finished and published what would become his most impactful novel, Slaughterhouse-Five. This was his opus and he told everyone who asked him in the time leading up to its publication that he had been working on "a novel about the fire bombing of Dresden."
Dresden is where Vonnegut was held captive in World War II as a prisoner of the already decimated Nazi forces. While a POW there, Vonnegut lived in an abandoned slaughterhouse funf, the inspiration of the title. It that building Vonnegut, his captors, and fellow prisoners of war waited out the sudden fire bombing of the citizen filled Dresden. Once they emerged from the building to survey the damage, Vonnegut saw a hell on earth he could have never imagined back home in Indianapolis. All the beautiful buildings were leveled and disturbingly, many of the city's citizens had been burned to their furniture where they had tried to hide from the bombers.
Vonnegut's job for the remainder of his time under captivity was to collect the charred remains of the German citizens and clear the rubble that used to be Dresden. So it goes.
HUMANITY: Vonnegut begins the novel by establishing himself as both narrator/character. He tells the reader his struggles to write the novel, and how he went and visited an old war buddy, O'hare, who also had a hard time remembering how things went and how they might be told. O'hare's wife makes Vonnegut promise that he won't write a silly war book that makes young scared boys look like macho heroes, and Vonnegut swears he won't. His intent is to show how ugly the destructive side of HUMANITY is and not glorifying how ugly and destructive people can be.
Vonnegut takes on the voice of the narrator throughout, and then his more direct character arrives in the end to speak with the reader about the story. This is a typical Vonnegut style choice that appears in most of his novels.
SO IT GOES/FREE WILL: This now famous Vonnegut phrase is used in Chapter 1. We see this phrase appearing when a character dies, witnesses tragedy, or is having difficulty with the passage or jumping of time. The Tralfamadorians (aliens) in the novel seem to push this philosophy forward--there is no free will, but only good attitude and humane treatment of one another will help make everything much more pleasant.
DISJOINTED NOVEL: By chapter two, we meet the protagonist of the novel, Billy Pilgrim. Billy is the one who will witiness the bombing of Dresden, marry, have a family, lose some of his family, grow a business, abandon the business, and eventually become "unstuck in time" as he communicates with aliens from the planet Tralfamadore. We follow Billy through these mundane and exciting moments of life as he jumps from experiencing one moment to the next, however, we are easily able to follow his life plot.
ESCAPE/WITHDRAWAL: In chapter 3, Billy is simultaneosuly living his moments as a prisoner of war on the way to Dresden and as a successful optometrist in Illium, New York. In both cases, he isn't fully present or passionate about the events taking place around him, and he begins to withdrawal and show signs of stress and mental instability. Vonnegut begins to warn about this withdrawal from life and is always stating that those who are struggling, "just need more people" around them. However, Billy continues to pull away from those moments in his life that are stressful and unpleasant.