Fredericksburg use to be in Comanche territory.
Is the verb "use" used correctly in this sentence?
No.
This verb should be in the past tense.
Fredericksburg used to be in Comanche territory.
No, because the verb should be past tense. The sentence is referring to Fredericksburg who is no longer in Comance territory.It is in the past that he is in Comanche territory.
The sentence should be:
Fredericksburg used to be in Comanche territory.