An experimental Starfleet tactical starship class of the 2370s that could split into three independent sections in combat.
The Prometheus-class was an advanced Starfleet tactical design developed in the 2370s. Its signature feature was multi-vector assault mode, in which the ship separated into three self-contained sections that could attack an enemy from different directions at once.
The prototype, the USS Prometheus (NX-59650), was also the first ship to carry the Emergency Medical Hologram Mark II. In 2374 Romulan operatives hijacked the prototype. Voyager's Doctor, sent across the galaxy through an ancient alien relay network, found himself aboard and teamed up with the reluctant Mark II hologram to retake the ship.
The events of Message in a Bottle gave Starfleet its first confirmation in years that Voyager had survived in the Delta Quadrant. The Prometheus-class showed how far Starfleet tactical design had advanced in the years leading up to the Dominion War.