Early Defenders of Yosemite - THE BUFFALO SOLDIERS
http://www.wildnesswithin.com/buffalo/soldier.html

I have to find the article but if I remember correctly an African American soldier was the officer of the guard (?) at Sequoia Nat'l Park and named the General Sherman and had it fenced off back in the mid 1800s.

I may have read it in American Legacy. I will check back issues.