Cass Henderson was born in space, has lived there for most of his life, and will in all likelihood meet an early grave there. Until then, the consummate military man in Cass will keep fighting for the ideals of the Federation. Cassius was born on the USS Callimachus, son of the executive officer and the chief tactical officer, both of British descent. The Callimachus was often on long patrols, due to its nature as one of the aging Excelsior-Class, so he grew up in space, learning with all the other fleet children until he was 18. During the final four years on the Callimachus, he was apprenticed to Warrant Officer Leonia Douglass, who was a tactical analysis, and she taught him the basics of human nature and how it relates to tactics. He then left for Starfleet Academy.

Arriving on Earth, he was assigned to Starfleet Academy’s London branch, which was geared more toward cadets who knew they would be specializing in tactical, flight control, and intelligence, also known as the hard departments. After some low marks at the beginning of his freshman gear, Cass settled into academy life and excelled in most of his classes for the final three years, even overcoming a hard year in advanced spatial physics his final year.

In 2373, he graduated at the top of his London class, just behind the head student at San Francisco. To celebrate, he and three other cadets, Susan deLiktos, Celia sh'Velta, and Zar, "borrowed" four Hawk-Class Tactical Fighter and dueled them with their weapons powered down. Nobody is quite sure what happened, but Susan’s craft nicked an asteroid and she sustained life-threatening injuries, and had to be towed back to Starbase 1, where all four cadets turned themselves in. After receiving a formal reprimand, they were allowed to graduate.

Feeling guilty due to Susan’s injuries, Cass and Celia immediately entered intelligence training, and were hidden from the world for a year, undergoing extensive training to prepare them for a covert mission against the Dominion. When they completed their work, they were assigned to the USS Saladin for a few months, preparing them for their work. Then they were granted promotion to Lieutenant JG and sent to their assignment.

Celia sh'Velta never returned from their joint mission. Though the still-classified mission's goals were accomplished, Cass Henderson came out of it all somewhat mistrusted by his superiors.

In 2375, a few months later, he was assigned to the USS Prospero as the ship's intelligence officer, also serving in tactical due to the Prospero’s role on the frontline. He served on the USS Prospero under Rear Admiral T'Paal at the for the remainder of the war, including the Battle of Cardassia, in which he was wounded in the line of duty, earning him the Purple Heart.

Later that year, he was promoted to Lieutenant Commander and assigned as the intelligence liaison to the classified research station on Dalson, near the Breen Neutral Zone. His assignment was to protect Doctor Aleksander Leontiev during the culmination of the experiments at Dalson Center. He failed, and Breen troops assassinated Leontiev and ruined the experiments, slipping past the security measures that Lieutenant Commander Henderson set up.

The review board had a field day with Lieutenant Commander Henderson's case, and he was found to be negligent in his duties as director of center security. He was demoted to Lieutenant JG, and SFI used the proceedings as an excuse to remove Henderson from their service.

Returning to Earth in disgrace, Cass attended school at the Starfleet Tactical College, intending to completely reinvent himself. In many ways he did. His intelligence career was over, and he found that he took easily to tactics and strategy, due to his analytical mind. He also became more withdrawn, more inclined to watch others go about their lives, fascinated by people's motivations.

In 2377, Cass returned to the USS Prospero as the ship's Assistant Chief Tactical Officer, and served there for over a year, earning a promotion back to Lieutenant, granted by Vice Admiral T'Paal. She recommends him for a position as Chief Tactical Officer, and he accepts transfer to the USS Havoc, a Steamrunner-Class Medium Cruiser.

In 2379, the USS Havoc encountered and defeated three Breen Medium Cruisers, protecting the convoy she was guarding against overwhelming odds. For his part in the encounter, including devising the maneuver that saved the freighters, Cassius Henderson was awarded the Golden Starburst, and the position of his choosing, as the USS Havoc was badly torn up.

After reviewing the list of open positions, he was assigned to the USS Galaxy, which had just lost its Chief Tactical Officer, who was moving to the USS Relentless-A as the Executive Officer. Having a good recommendation from Vice Admiral T'Paal as a former commander seems to have helped in the application process.

Less than 6 months later, Lt. Henderson was promoted to Lt. Commander.

After Commander von Ernst transferred off the Galaxy in mid-2380, Cassius was brevet promoted to Commander and placed into the Executive Officer slot by Captain Eliza Stuart while she temporarily commanded the Galaxy while Captain M'Kantu was called away to Earth for debriefing on the previous mission to Quentin.

Upon Captain Stuart's recommendation, Cassius was promoted to Commander and permanent Executive Officer of the USS Galaxy.

Cassius Henderson was given his first command when Captain M'Kantu was temporarily relieved of duty in November 2382.

Henderson was given his first official command shortly before the Battle of ch'Rihan.

Unlike his commanding officer, he would like to consider himself to be a follower of Ambassador Spock's "Dove" movement, but in reality knows that he has it in him to be a far harder man than he likes to admit.

He can be something of an idealist, though, and firmly believes in equality of races and sexes, something which he had butted heads with the more xenophobic members of SFI over before his transfer.

Family:
Rear Admiral Alaric Henderson – Father - Commanding Officer, Task Force 171,
Captain Kaitlyn Henderson – Mother - Commanding Officer, USS Callimachus,
Lieutenant JG Elisabeth Henderson – Sister - Assistant Chief Flight Control Officer, USS Tiberius

Cassius Henderson attended one of the first Advanced Tactical Schools in the sector. It was independently run by former Admiral Kjell Eriksson in Glasgow, Scotland, as Starfleet Command refused to officially endorse it, as it was promoting a slightly more militant stance. (Eriksson preferred the term "defensive") Since Eriksson’s untimely demise at Wolf 359, Glasgow Independent Advanced Tactical School, or GIATS, is run by former Captain Irene deMercereau, now Fleet Admiral and commander of the 5th Fleet.

Cassius has a tendency to stand to the side and watch people interact, usually only offering his opinion if asked or at the end of the conversation, if he feels particularly strongly about the topic. He tends to write down his observations on a PADD which he keeps in his quarters.