In 2251, the USS Republic, under the command of Captain Rollin Bannock, was dispatched on routine training mission near the Neutral Zone. One night, the Republic was assigned a classified mission which meant that all cadets aboard, including James T. Kirk and Gary Mitchell, were confined to crew quarters for the duration. (TOS - My Brother's Keeper novels: Republic, Constitution) These references to a Klingon Neutral Zone prior to the Organian Peace Treaty likely refer to an earlier Federation–Klingon border, which was likely redrawn with the Treaty.