I finally got the joke

The Rocky and Bullwinkle jokes are famous for their wit.

For example, villain Boris Badenov is named because he is certainly "bad enough" for anyone. And there is a famous Russian opera Boris Godunov, which is based on the life of Boris Godunov (c. 1551-1605) who became Tsar of Russia from 1598 to 1605. And there is an English surname Goodenough used by several famous persons.

I recently (sometime in October 2017) saw online the Peabody's Improbable History episode "Geronimo" for the first time in decades and finally got one of the jokes. I probably saw it when it aired the first time or the first time it reran.

https://www.youtube.com/watch?v=iU8TbLza3qY

Here we see that it aired with the first episode of "Topsy Turvy World":
https://en.wikipedia.org/wiki/Topsy_Turvy_World

And here we see that the first episode of "Topsy Turvy World" first aired on January 7, 1962.

http://www.tv.com/shows/the-bullwinkle-show/episodes/

http://www.imdb.com/title/tt0054524/episodes?season=1&ref_=ttep_ep_sn_pv

Which was about 55 years and about 9 months before I got one joke. Okay, I might have got the joke before, but if I did I must have forgotten it, because I realized it in 2017 after seeing the episode and wondering about it.

The episode starts as Mr. Peabody and Sherman go back to 1886 to witness the signing of a peace treaty between Geronimo and General Crook at Fort Heathen. And Fort Heathen is a very strange name for a US army fort. They are usually named after high ranking officers like Fort Halleck or civilian officials like Fort Abraham Lincoln. It was rare for a fort to have any other type of name.

But Fort Apache, Arizona, was named in honor of the Apache Indians after earlier being called Camp Ord and Camp Thomas after famous generals. Apparently it was renamed Camp Apache in 1871, and so possibly as a diplomatic gesture by General Crook who became commander in Arizona in June 4, 1871 and made big use of the local White Mountain Apaches as scouts against the hostile Apaches..

As you may remember, the pun at the end of the "Geronimo" episode explains that the Apache Indians got their name because of an event in the episode. So they weren't called Apaches at the beginning of the episode.

And the Indian wars fort in Arizona that would be most familiar to the public in 1962 was Fort Apache, the setting for the famous movie Fort Apache (1948) and reruns of The Adventures of Rin Tin Tin (1954-59). So I realized that in the episode Fort Apache was called Fort Heathen as a sort of generic term because the Apaches weren't called Apaches yet!