Ian's Starfleet history has not seen a great deal of action. In his younger days as an engineer, he took part in the Tzenkethi war near the Cardassian border. He got seriously injured and was returned to Earth for treatment. After a few years of recovery, he was given a desk job at Starfleet academy. After eight years of this, he decided he needed a change and requested a transfer to an active ship.
He was transferred to the USS Okuda where he became chief engineer in under a year. Now a Lieutenant Commander, he was transferred to an outpost at the far reaches of the Alpha Quadrant, although being on a frontier, it was a relitively quiet assignment.
He took one more promotion here to Commander, and Starfleet reassigned him to Commander of the station. He performed exceptionally in this role and quickly became a Captain at age 49. Five years later, he was granted command of the USS Scorpio. 2 years later, the Mulluran war broke out and the Scorpio was sent to the front lines. In one of the ensuing battles, the Scorpio was destroyed. All of teh crew escaped and were returned to Starbase 901 to await reassignment.
When Captain Evans of the USS Ronin was lost in the line of duty on a mission in the Briar patch, Waters, being the closest unassigned Captain, was given command of the USS Ronin.