Home in time of Confusion

In chapter 7 of Slaughter House Five, not much happens. Vonnegut does, however, tell us about Billy’s plane crash. When he was rescued, he overheard his Austrian helpers speaking German, and in his confusion, muttered to them his address: “Schlachthof-funf.” Slaughter House Five, his home during his stay in Dresden. It’s weird that of all things to say in such a moment, Billy chooses his address in Dresden.
This is huge. It's as if the only thing that becomes clear is this memory. Not his name, not his kids or wife, not his home in Ilium. Not even "Help." The only clarity in his life is Slaughter House Five and Dresden.