For decades, a growing segment of the Pathfinder Society's membership became disillusioned with the Decemvirate. Whether they held personal grudges against the masked leaders of the Society for slights they felt were never remedied or watched too many of their friends suffer for the good of a Society that seemed to thank them very little, these rebels' numbers surged in the early 4700s AR, swelling the Shadow Lodge's membership. In 4710 AR, several fringe cells of the underground resistance movement broke off from the main body of the Shadow Lodge and began a series of open attacks on the Grand Lodge and those loyal to it.
The Decemvirate, recognizing that there was a real problem to be addressed, quelled the rebellion by bringing the Shadow Lodge back into the fold, acquiescing to some of their demands, and sending strike forces to hunt down and eliminate remaining cells of radical Shadow Lodge agents. Many still feel the Decemvirate has further to go to remedy the injustices carried out in the Society's name, though they are glad to be in good standing with the Society once again—even if many also believe they were brought back into the Grand Lodge so the Ten could keep a closer eye on them.1
Goals: Hold your leaders accountable
Members of the Shadow Lodge hold the Decemvirate accountable for its treatment of field agents and the consequences of its missions.2
For additional as-yet unincorporated sources about this subject, see the Meta page.