It's not often that a top-rated TV series is cancelled unceremoniously, but strange things happened in the 1960's, and in this case the victim was the series The Wild Wild West(TWWW).
TWWW premiered in 1965, the same year as other great series such as Hogan's Heroes. It rose quickly to the top of the Nielsen ratings for a number of reasons: 1) the star, Robert Conrad, was a real heartthrob for young women of that time 2) the series was novel and nothing like it had ever been on TV before 3) it had everything that young men of the time wanted - fantastic gadgets, beautiful women, lots of violence, animated sequences, and 4) a recurring supervillain. From the IMDb:
In 1965 someone had the bright idea to mix the two most popular genres at that time, spy shows and westerns, and came up with this classic series. The western elements were obviously the horses, Indians and a strong hero and the espionage elements were the gadgets and megalomaniacal villains. Robert Conrad was excellent as Jim West and Ross Martin was just as great as the master of disguise Artemis Gordon. The chemistry between the two leads helped to make this show a classic. However, Michael Dunn pretty much stole the show as supervillain Miguelito Loveless, or as Artie would often call him, "The Little Wizard".
Eventually the series became the victim of its own success, as it had to become more outrageous and more violent to retain its core audience. By 1968, the program was one of the most violent on TV, and then something unforeseen happened - the assassination of Robert Kennedy.
Kennedy's murder brought about the Gun Control Act of 1968, and it also caused the three networks to purge their most violent offerings, among these TWWW. No matter that it was one of the top-rated TV shows, it had to go and was axed. Robert Conrad was most vocal about the unfairness of it all, but to no avail. Welcome to Syndication Hell, Mr. West.
YouTube contains many if not all episodes, although their video quality may vary widely. Below are embedded a couple of those that are directly available; all seem to be available indirectly.
Regarding the animated sequence shown above, the 4 areas featuring other characters changed during the episode, with a freeze-frame drawing of the action seen at the break replacing one segment, until all were changed by the end of the episode. Originally, the cowboy kisses the woman intent on stabbing him. Later episodes showed the cowboy knocking the woman down instead. And then they wondered why it was canceled.....