Welcome to the forum,
Treknicalities 
TOS history buffs are always welcome here. Hope you enjoy the forum.
Off the top of my head, the only preemption I know of is
Turnabout Intruder, which was pushed back several months in 1969 due to the death of former president Eisenhower.
This fantastic website has just joined my bookmarks list - I think it has all the info you're after.
Seems
Star Trek was replaced by football games, comedy specials, moon landings, circuses - you name it, Trek got replaced for it
