"Saber" is the popular term for a nameless militia formed in the Badlands during the Second Infinitas War. The group was in opposition to the rather oppressive policies of the Trade Union and the way it treated it's citizens in Marsilion, many of whom were not in favor of the war to begin with despite it being fought using their own tax money.
The organization was initially a sleeper group created by the-then-still-a-citizen Daniel Muir, and staffed by part-time citizens from the metro area, who set up a base of operations to gather and disseminate information of Trade Union activities in order to inform the citizenry. The group was kept unnamed, and often referred to itself by various pseudonyms in order to ensure the security of it's members, who were doing rather dangerous work. Many were informants inside Marsilion society.
When the Trade Union responded to subversive broadcasts by jamming signals and arresting radio broadcasters as well as censoring the media, Saber became more vigorous in it's attempts to discredit the Trade Union. It was not until the Southeastern Square Massacre, however, that Saber, as it would be later called, sprung into action. It was decided that the Trade Union had to be overthrown.
More pessimistic members of the group or those who had heard of it were skeptical. The Trade Union had dozens upon dozens of small-time mercenary companies working for it and was working to reinforce them from day one of the war, and were only growing more powerful with time. The 'militia', as it was simply known, was said to have composed only 80 members at the start, although that number has drawn questioning from many, as the events that followed are hard to imagine being accomplished by such a small number of men.
Despite internal fracturing and sometimes disasterous power struggles, the group remained under Muir's leadership and organized itself, striking boldly and decisively at a number of places. Using the talents of it's members and offworld salvage, including a plane that they christened Scorpion, they struck at all comers who threatened them, Fighter, Mage and Trade Unionist alike. Constantly relocating and raiding Trade Union holdings, their reputation grew, and soon they had many informants and men in many different locations, all working to sabotage the system from the ground up.
The Trade Union had launched most of it's troops in a much-publicised amphibious invasion of Arcford, which was intended to make the Fighters widthdraw, as it was believed that their grip on the city was tenuous. The results were anything but. Having been bogged down in house-to-house fighting, Marsilion was left vulnerable, it's garrisoning force much smaller than it would have otherwise been. Still, the Trade Union lords were disbelieving of the threat that Saber posed, believing the reports to be exaggerations and the casualty counts to have been caused more by friendly fire.
The Battle of Marsilion proved them decidedly wrong. Their raids having grown them in strength to over 800 members, including Scorpion and several captured prototype tanks, Saber launched a lightning thrust into Marsilion and soundly decapitated the Trade Union government, capturing or killing warlords along the way. Under complete panic, each of the Trade Union lords attempted to protect their own estate, and as such they were unable to mount an effective response to Saber's shock tactics, and the city fell. Many mercenary groups saw which way the wind was blowing and defected or broke contract and left. In only an hour, the Trade Union fell.
The group's name comes from the events of this battle. Civilians, eager to join the fight and gather weapons, overheard the radio chatter of the group as they blew their way towards the capitol building. The assigned codenames for the tanks during the invasion was "Saber" - Saber 1, Saber 2, etc. Lacking a name still after all this time, the civilians took to calling the group Saber. Muir realized, after it was all over, that he'd been so focused on defeating the Trade Union that he had neglected to ever give the group a proper name, and Saber seemed as good as any, and so it has been officialized in the War Memorial.