What was wrong with the 18th?

A couple of weeks ago, I was doing some research and came across this account of a Federal POW jumping a train as it traveled from Danville to Charlotte. He left this description of part of his adventures. A small part of the 18th North Carolina came from Wilkes County, where the POW was passing through. So, what was wrong with the 18th?

"...Gorham approaches the door and raps. The door was opened by a lady about forty years of age. 'What will you have sir?' she says. 'Madam, I am hungry, I wish to procure some food, can I do it here?' 'I have nothing for you,' she replies, as she partly closes the door.

   "Seeing he was inclined to urge his request no further and was about to leave, she says 'You belong to the 18th don't you?' 'No,' he says, 'I am an escaped Yankee prisoner.' From the nature of her question and its inflection he saw that the 18th she referred to must be the 18th North Carolina, and that she had little sympathy with them, so he concluded to argue the case on its merits at one. 'Is that so?' she says 'God bless you, come in here.' from Francis J. Hosmer, Andersonville and Other Writings (1896), page 5.