Mackey's Landing on the Roanoke River (between Williamston and Plymouth NC)
Edit - lelliott19, I could not find any source that explicitly confirms your answer, but I'm going to count it as correct.
The answer that was easy to find (and the one that just about everybody else found) was Plymouth, NC, though some sources indicate that Union troops were captured at Fort Williams, just outside of Plymouth.
I searched for Mackey's Landing and all I could find was that it is the name of a firearms store in Jamesville, NC. I couldn't find anything to indicate that Jamesville was the site of Fort Williams, but it is, as you said, between Williamston and Plymouth, and I think that's close enough that I can give you credit for your answer.
Hoosier