Portions of Fire in the Lake were serialized by The New Yorker in the summer of 1972. They are available below via the magazine's online archive.
"Vietnam I: Fire in the Lake" (July 1, 1972)
"Vietnam II: Sovereign of Discord" (July 8, 1972)
"Vietnam III: A Cave on Karl Marx Mountain" (July 15, 1972)
"Vietnam IV: Johnson's Dilemma" (July 22, 1972)
"Vietnam V: Survivors" (July 29, 1972)