UNITAS, Latin for Unity, is the longest-running multinational maritime exercise in the world. A U.S.-sponsored joint exercise, UNITAS was conceived in 1959, with the first UNITAS (UNITAS I) taking place in 1960. UNITAS has occurred every year since then. When it started, U.S. and partner nation organizers decided to use Roman numerals to highlight the significance of a multinational maritime exercise designed to increase interoperability and strengthen partnerships among participating maritime forces. Exercise documents and host country branding still feature Roman numerals today, more than 60 years later.