Several explanations exist for the origin of the nickname of the University of North Carolina athletic teams. The first simply notes that the school carries the nickname because the state is known as “The Tar Heel State.”
A second story goes back to the Revolutionary War period. Troops of British General Cornwallis, while crossing the Tar River between Rocky Mount and Battleboro, discovered that tar had been dumped into the river to hinder their advancement. After finally reaching the other side, the soldiers found their feet covered in tar. The British then surmised that anyone fording a North Carolina river would exit with tar heels—hence, the nickname.
A final tale dates to the Civil War. State Archivist David Olson, in 1991, found a letter dated August 24, 1864 written by Major Joseph Englehard detailing the stout efforts of men from North Carolina during a battle near Petersburg, Virginia. Englehard overheard General Robert E. Lee declare, “There they stand as if they have tar on their heels.”
Whatever the truth, the University of North Carolina has one of the more unique nicknames in sports!

This article is based on information from the official website of North Carolina athletics, goheels.com.