September 18, 1966 (A rare instance of an adult being given a speech bubble in a 1960s strip)
September 19, 1966 (Beginning of a storyline in which Snoopy's doghouse burns down, this is also the third time it was destroyed. It was destroyed for the first time on July 26, 1959 and for the second time on February 13, 1960, Charles Schulz made this comic to express his feelings after his Sebastopol studio burned down)