Book 15 in the Star Trek: Enterprise series.
When a new threat emerges from a force so alien and hostile that negotiation seems impossible, a group of unaligned worlds asks Starfleet to come to its defense, and the Federation’s leaders seize the opportunity to build their reputation as an interstellar power. But Archer fears the conflict is building toward an unnecÂessary war, potentially taking the young nation down a path it was never meant to follow. Archer and his allies strive to find a better solution...but old foes are working secretly to sabotage their efforts and ensure that the great experiment called the Federation comes to a quick and bloody end.