Nicholas Theron Tattnall was born 44 BTF in the city of Auburn on Caprica. He was the oldest of five children. His father, Josiah Tattnall, Jr., was an Executive Vice President with Meinrad Industries. His mother, Abigail Tattnall, was a member of the Auburn City Hall Public Relations Division. He has a younger brother named Noah as well as triplet sisters Nadia, Nadine, and Nadira.
Upon graduating from Gray Station High School Tattnall was accepted to Abry Military Academy. After graduating he was made an officer in the Colonial Fleet. His first posting as an Ensign was to the Battlestar Lemnos as a Viper pilot. Tattnall would stay on the Lemnos until he was promoted to Captain and posted to the Battlestar Xanthus as a squadron leader. When the time came for his next promotion he was made a Major and posted to the Battlestar Romulus as CAG. He stayed on the Romulus after his promotion to Lieutenant Colonel and moved to the Tactical Division. He was promoted to Colonel and assigned to the Battlestar Formidable as Executive Officer.
Three years BTF he was summoned to the Colonial Fleet Bureau of Ships on Picon for a meeting with Rear Admiral Scott Tolan. Tolan informed Tattnall that he was being promoted to Commander and being given command of the decommissioned Battlestar Libran. The Libran was in the process of being reactivated for the purpose of eliminating the pirate group Erebea, and Tattnall was going to lead the charge as the Libran's Commanding Officer.