Leon Vance's Entire NCIS Backstory Explained

Vance grew up in Chicago, where he trained to be a boxer (detailed in the Season 6 episode "Knockout"). He later attended the U.S. Naval Academy, where he was commissioned with the rank of Second Lieutenant. In 1991 Vance was a student at the Naval War College, where he became fascinated with black operations. Approached by the NIS (the precursor to the modern NCIS), Vance was recruited by Special Agent Whitney Sharp (in a flashback from the Season 8 episode "Enemies Domestic").

Trained by Sharp, Vance joined a clandestine NIS mission codenamed Operation: Trident and tracked down a mysterious agent known only as The Russian. Vance had his first encounter with Eli David (Michael Nouri) on the mission, who warned him that the Russian was aware of the operation and intended to kill Vance. Eli then betrayed Vance to the Russian, but this turned out to be a ruse to lure the villain out so Eli could kill him. The Russian escaped, but Eli and Vance took out his hit squad, and Vance soon found himself rising through the ranks of the NCIS for his handling of the situation.