In short, Enterprise needed a big change, and the Xindi provided it. In the season 2 finale “The Expanse,” a new alien race called the Xindi (a people comprised of six different species) launch a preemptive attack on Earth, destroying a huge swath of the planet and killing the sister of Enterprise’s Commander Trip Tucker. The attack forces Enterprise to change its mission, coming back to Earth for a refit and then preparing to take the fight to the Xindi.
The Xindi War would span across season 3, and would include some classic Trek concepts. We’d see characters like Trip dealing with loss, we’d see humans form alliances with alien species, and we’d see how conflicts stem from misunderstanding. In particular, the third season reveals that the Xindi attack Earth because mysterious, malevolent aliens called the Sphere-Builders convince them that they will be killed by Earthlings. Moreover, Archer succeeds in his mission by forming a connection with Degra, a humanoid Xindi who comes to trust Archer and recognize the Sphere-Builders’s deceit.
Compelling as that sounds on paper, the execution left much to be desired. Archer was always written with a chip on his shoulder, due to the way that Vulcans disrupted his father’s career, and that chip only grew deeper after the Xindi attacked Earth without provocation.
Worse, the war made cruel soldiers out of Trip and T’Pol, the show’s two best characters. For three out of the four seasons, Trip was a folksy engineer who tackled complex problems with down-home charm, while T’Pol was a Vulcan who overcame her prejudices to connect with the human crew of the NX-01. But once his sister dies, Trip becomes consumed by vengeance and righteous anger, calling for the execution of those who wronged him (it doesn’t help that his twang makes him sound like the decider himself, George W. Bush). T’Pol’s shift isn’t as spectacular, but her frustration with the Vulcan Council’s inaction drives her to defy them and their rules, making her into something of a maverick who has no use for laws or treaties.
By the time the storyline ended with the season 3 finale “Zero Hour,” Archer and his crew had become blustering cowboys, jingoists who will only work with others if they form a “coalition of the willing” to go attack the terrorists, sacrificing Federation ideals in the process.
But that’s not the real problem. The real problem is that Battlestar Galactica was doing it better.
