David Letterman got his jabs in at Jay Leno by featuring his very own "Jay Leno File" — a segment including mentions of the host's "failure in prime time," his ousting of Johnny Carson from The Tonight Show and a little-known "incident" with Jimmy Stewart in 1989. If this were a real FBI file, they might have a case.
Top 10 Moments from the Late-Night War
As Conan O'Brien quits The Tonight Show and Jay Leno prepares to retake his old time slot, tensions are running high at NBC — and so, surprisingly, are ratings. TIME takes a look at some of the late-night feud's best moments