Why must state laws agree with the u. s constitution?

because u have to follow the laws of the founding father and the constitution and if the laws don't have the laws in them then it would be breaking the law.

in 1897, pershing became a tactical officer at west point, and that's where he was given the nickname "black jack." pershing's first name is "john," for which "jack" is a nickname, and he was a white man who commanded black troops. hence "black jack".

which time period is this? or is this story fictional, i'm going to need more info to answer this question