as the Maquis. Rooted in the events of The Next Generation episode "Journey's End", in which Native American settlers refuse to leave when their planet is given to Cardassia as part of a treaty, the Maquis are an example of the show's exploration of darker themes: its members are Federation citizens who take up arms against Cardassia in defense of their homes, and some, such as Calvin Hudson, a long-time friend of Sisko's, and Michael Eddington, who defects while serving aboard the station, are Starfleet officers. The show's critique of traditional Star Trek themes can be seen in episodes such as "For the Cause", in which Eddington compares the Federation to the implacable alien hive mind known as the Borg: "At least [the Borg] tell you about their plans for assimilation. You assimilate people and they don't even know it." The Dominion War The second-season episode "Rules of Acquisition" marks the first mention of the Dominion, a ruthless empire in the Gamma Quadrant, though they are not fully introduced until the second-season finale, "The Jem'Hadar". It is led by "the Founders", a race of shape-shifting Changelings, the same species as DS9's security chief, Odo. They were once persecuted by non-shape-shifters (whom they call "solids") and they seek to impose "order" upon any who could potentially harm them, which includes nearly all solids. The Founders have created or genetically modified races to serve them: their sly diplomats and administrators, the Vorta, and their fearless shock troops, the Jem'Hadar. These races worship the Founders as gods. At the start of DS9s third season ("The Search"), with the threat of a Dominion attack looming from the other side of the wormhole, the USS Defiant, a prototype warship, is stationed at Deep Space Nine, providing an avenue for plot lines away from the station. With the third season, writers from the now completed The Next Generation began to write regularly for DS9. In the middle seasons of the show, the Dominion foments discord to weaken the Alpha Quadrant powers, manipulating the Klingons into war with the Cardassians and almost inciting a coup d'état on Earth. In the fifth-season episode "By Inferno's Light" the Dominion annexes Cardassia, and goes to war with the other major powers of the Alpha Quadrant in the season finale "Call to Arms". The Dominion War tests Starfleet's commitment to its ethics; when the formerly neutral Romulans are persuaded to ally