In case you've read about but never seen perhaps the most famous "negative" TV spot ever created: the 1964 "daisy" as for LBJ suggesting that Goldwater would get us all killed (starting with that cute little girl) in a nuclear war if elected. There was long debate over whether it never aired or aired a couple of times and got pulled. Even Don Draper has commented. Now it seems it aired ONCE in September 1964, then halted--although then shown in its entirety on the nightly news shows, so millions did view it. Bill Moyers, who worked for LBJ, said at the time, "The idea was not to let him [Goldwater] get away with building a moderate image and to put him on the defensive before the campaign is old.”
Note: The first attack ads on the screen date from 1934 and were created by....Irving Thalberg.