Shortly thereafter, Nelis Saler chose to enter Starfleet Academy on Earth. While there, he took an interest in starship tactical operations, choosing that as his field of specialty. Upon graduating around the middle of his class, Saler was accepted (barely) into Starfleet's Advanced Tactical School in Glasgow. Here, however, Saler managed to distinguish himself, graduating third in his class, and catching the notice of the commandant of the school at teh time, Captain Irene deMercereau.

Saler was first assigned to the U.S.S. Tecumseh, where he would spend the first five years of his career, rising to the rank of lieutenant and the position of assistant chief tactical officer under the watchful eye of Captain T'Lura. Entering a brief romatic relationship with another officer, Lieutenant Sari Bhutto, Nelis intended to remain on the Tecumseh for several years to come. He had little ambition to rise beyond his position or rank, and enjoyed the enviornment he was in. However, when Bhutto was killed on an away mission in April of 2369, Saler transferred immediately off the ship, vowing never to enter into another romantic relationship with a fellow officer, and concentrating on nothing more than his career.

Saler's transfer earned him a promotion to lieutenant commander, and a position as the chief tactical officer of the starship Winfield. From this point forward, the newly ambitious officer's career moved rapidly. Fewer than two years after transferring to the Winfield, Saler was selected as the executive officer of the starship Wells, and a year-and-a-half later, he had his own command, the Miranda-class U.S.S. Majestic.

The chief flight control officer onboard the Majestic was Lieutenant Commander Lawrence Emerson-Davies, son of Master Chief Petty Officer Ambrose Emerson, Command Master Chief of the Seventh Fleet. The assistant to Emerson-Davies was an ambitious lieutenant (jg) named Juan Holmes.

The thirty-four year-old captain and his crew were assigned to the Sixth Fleet, on missions protecting the ever-tenuous border between Cardassian and Federation space. Majestic took part in several engagements during the short Klingon War in 2373, and when the Dominion War broke out, she was one of the ships to rendezvous with the Defiant and Rotarran when Deep Space Nine was evacuated.

For the next several months, the Sixth Fleet was heavily engaged in various actions of the Dominion War. The Majestic was a part of these actions, and on the eve of Operation: Return, the ship was assigned to the 74th Battle Squadron, under command of Vice Admiral deMercereau. In the course of the battle, the Majestic and her sister ship the ShirKahr were assigned as the flanking vessels for the Defiant. Six-thousand meters from the perimeter of the battle, the Majestic was struck by several blasts from a Dominion battlecruiser, annihilating the ship's forward superstructure. Nearly one-humdred members of the crew were killed immediately, and the eventual death toll would rise to 163 of the Majestic's 214 crewmembers.

Several of the Majestic's survivors were with the ship's fighter squadron, including Holmes. Saler was among the remaining forty-three survivors. Emerson-Davies was not. Ordering the ship abandoned, Saler launched in one of the escape pods leaving the ship. The Majestic was later towed from the debris field left in the battle's aftermath and sent to a Federation scrapyard, until the derelict hulk was rescued in 2377 by Holmes for conversion into a new form of escort carrier, renamed the U.S.S. Chamberlain.

An official court-of-inquiry in the aftermath of the battle decided that, despite the massive loss of vessels and life during the engagement, that the Majestic was an exception, and that her destruction could have been prevented. Captain Saler was deemed to have been at fault for the loss of his ship for not ordering evasive action be taken to avoid being struck by the attacking battlecruiser that he never even saw coming.

Relieved of his duties and reverted to the rank of lieutenant, Saler could find no assignment until Lieutenant Commander Jadzia Dax, a former classmate of Salers at both the Academy and the Trill Sybiosis Institute, convinces Captain Sisko to request Saler's assignment as an intelligence officer on the station. Jadzia is killed shortly before Saler's arrival, and he arrives just in time to meet the new host of the Dax sybion, Ezri.

Captain Sisko, who, having been present for the destruction of the Majestic, did not consider it the fault of Saler, was very protective of the disgraced officer, and upon his disappearance, these responsibilities were mirrored by Colonel Kira.

Saler spent nearly five years on the station performing his new duties. However, he was a changed man once again. Just as the death of Sari Bhutto had affected him, so had the loss of his ship. Though he did not lack ambition, he felt that Starfleet would never promote him again, and so he resigned himself to repetative duties. Rarely leaving the station, Saler picked up a fondness for the Bajoran people, and when he did venture off of Deep Space Nine, it was to the nearby planet. Usually, however, he could be found in Quark's, sitting at the bar, staring at nothing in particular. It was here that Irene deMercereau found him.