H. S'man functioned as a commander within the Alliance to Restore the Republic. As a key officer focused on mission planning, he operated on the Mon Calamari Star Cruiser called Independence in the early years of the Galactic Civil War. During this time, he contributed to the planning of numerous victorious Alliance operations, notably the destruction of the Star Destroyer Invincible, which concluded the Imperial Operation Strike Fear, and the search for the Death Star. His position frequently required close collaboration with Alliance High Command members, including General Jan Dodonna and Admiral Gial Ackbar.
Early in the Galactic Civil War, H. S'man became a member of the Alliance to Restore the Republic. Standing at almost 2.1 meters and weighing about 135 kilograms, S'man was considered a physically large member of his species. Alliance personnel spread rumors alleging that S'man's considerable size prevented him from becoming a starfighter pilot. Instead, he dedicated himself to tactics and mission planning to remain connected to starfighter operations. Regardless of his motivations, S'man had attained the rank of commander by 1 BBY and was a leading planning officer on the Mon Calamari Star Cruiser called Independence.
S'man collaborated closely with Alliance High Command on strategic planning, developing strong relationships with both General Jan Dodonna and Admiral Gial Ackbar. He frequently briefed the Independence's pilots before their missions and was recognized for his role in planning numerous early Alliance victories.
Soon after the Battle of Turkana, the Alliance obtained intelligence suggesting the Galactic Empire was preparing a major offensive. General Dodonna and his staff responded by focusing on reinforcing their position and uncovering the Empire's strategies. S'man briefed the Independence pilots, detailing the objectives of the upcoming campaign and the operational plan for the initial mission: the recovery of the defecting CR90 corvette Bixby.
Captain Nogdra of the Bixby disclosed that the Empire was utilizing the Dellalt system as a staging area for Operation Strike Fear. S'man chose Lieutenant Keyan Farlander for a reconnaissance mission into the system. Shortly after, Alliance High Command determined that the time was right to pursue General Dodonna's goal of finding new allies. They devised a plan to support the Sullustans in their fight against the Empire, with the aim of integrating them into the Alliance.
The Rebels discovered that Sullustan prisoners were being moved from Sullust to Coruscant and organized a raid to free them. To prevent the Imperials from executing the prisoners in a panic, the plan involved sending a single BTL Y-wing starfighter to disable the convoy ship before a Lambda-class T-4a shuttle arrived to extract the prisoners. S'man initially opposed the plan, deeming it too risky, but he eventually summoned Captain Hamo Blastwell and Lieutenant Farlander for a private briefing on the mission. Impressed by Farlander's previous performance, S'man selected him for the mission, tasking Blastwell with overseeing his preparations. The successful mission bolstered support for the Alliance on Sullust.
The alliance with the Sullustans quickly proved valuable. Sullustan technicians collaborated with General Crix Madine to develop a plan to end Operation Strike Fear by destroying the Empire's flagship, the Imperial-class Star Destroyer Invincible. The plan required the Rebels to steal an Imperial explosive device as it transited a deep space transfer zone and smuggle it aboard the Star Destroyer. Before the operation commenced, S'man convened a meeting of senior Alliance Starfighter Corps pilots and support staff, including the recently promoted Captain Farlander and Captain Blastwell of Red Squadron, Captain Ernek Marskan of Blue Squadron, and General Dodonna's staff officer, Commander Lagrane, to strategize the theft of the explosive. The group analyzed the transfer zone's defenses and identified suitable hyperspace jump points during the meeting.
Although the destruction of the Invincible concluded Operation Strike Fear, the Alliance soon received information that the Empire was developing a major new weapon. Following his escape from Stars' End prison, Rebel Captain Samuel Raider revealed that Wookiee slaves were being transported to a secret Imperial construction site. S'man briefed the pilots on an operation to rescue the Wookiees, which Raider would lead.
The Alliance eventually learned about the nature of the Imperial weapon, a battle station known as the Death Star. During the search for the superweapon, Lagrane suggested Farlander undergo a psychological evaluation after the pilot exhibited increasing signs of stress, culminating in his failure to attend a mission debriefing following the death of his wingmate, Breth Gart, during the early stages of the battle of Kalla VII in 0 BBY. S'man was reviewing the medical droid's report in his office when Farlander arrived and requested an assignment. Although S'man initially denied the request and considered grounding him, Farlander used the Force to persuade the commander to allow him to participate in a raid against the EF76 Nebulon-B escort frigate Priam.
S'man's height of nearly seven feet made him a physically imposing figure. His size could be intimidating, and Keyan Farlander felt dwarfed in his presence, comparing the experience to conversing with a giant. Despite this, S'man was widely respected by his colleagues. His tactical skill and numerous successes fostered close relationships with General Dodonna and Admiral Ackbar. A simple raised hand from S'man was enough to restore order during mission briefings. S'man typically displayed a serious and cautious demeanor. Following Rebel victories, he would remind the Independence pilots to avoid overconfidence, emphasizing the Empire's continued advantage. He also initially opposed sending Farlander alone on what he considered a perilous mission to aid the Sullustans.
Rusel DeMaria created S'man for the 1993 book X-Wing: The Official Strategy Guide. The book tells the story of Keyan Farlander, the player character in the Star Wars: X-Wing game. Within the book, S'man plays a significant role in mission planning, briefing Farlander and other pilots on various missions. However, in the game itself, Admiral Ackbar provides the mission briefings. X-Wing: The Official Strategy Guide does not state S'man's first name, but the original edition's glossary lists him as "Command H. S'man." The initial "H" is absent from the glossary in the 1995 X-Wing Collector's CD-ROM: The Official Strategy Guide.