"Listen: Billy pilgrim has come unstuck in time" (Vonnegut 23).
What does this mean?
The moment Billy first becomes unstuck in time is when he is behind enemy lines. He jumps forward beyond death, and jumps back before birth. Basically he travels through time with little control over where he goes.
Themes to consider: Lack of Freewill, Time Travel
Billy goes to war.
We find out that Billy gets drafted to war in Chapter 2. Its 1944, and he gets sent to Germany to fight in WWII.
Billy becomes a prisoner.
The reason that this is such a major point in the book, is because it further demonstrates how Billy is always under control of other people. Billy starts experiencing time out of order because of his traumatic encounters.
Billy witnesses the firebombing of Dresden.
This is so traumatic because after all that has happened to him, he survives a city going down in flames. He witnesses so much death, which is a major moment in Slaughterhouse Five.