In the aftermath of Gije's Sublight missile attack on the colony of Ajian, Commodore took command of the remaining population. When the Solo Ship arrived, Commodore made a deal with Buff Clan commander Dron, planning to exchange the colonists in return for supplies for Ajian.
However, Commodore's hatred of the colonists led to him seizing their women and children, tipping Bes off that something was up. Commodore executed Lin to prove the was serious, but Bes led a squad of troops to infiltrate the amphitheatre where the hostages were held. Commodore's men were taken out by snipers, while Sheryl gunned down Commodore with Bes' pistol. Badly injured, Gije finished him off out of compassion.
His spirit was reunited with that of his wife Maria after the Ide wiped out both the humans and the Buff Clan.
Commodore's name isn't given - unless Commodore is his name (there is, after all, a character named Marshall). He isn't seen in episode 18 - given his brown uniform (which generally means a lower-level soldier) he probably wasn't particularly high-ranking and has only risen to a position of power through the attrition. Considering what a bitter guy he is when we meet him, it's fair to presume Maria was killed in the initial attack on the planet.