From FreeSpace Wiki
The Vega Engagement occurred circa 2333 between the Galactic Terran Alliance and the Parliamentary Vasudan Navy, during the Terran-Vasudan War. A major defeat for the GTA, the engagement was notable for being the first known combat deployment of the dreaded PVD Typhon-class destroyer. A disastrous underestimation of the new warship's abilities on the part of Terran engineers resulted in the destruction of the GTD Eisenhower and the total decimation of the Terran 4th Fleet. This turned the tide of the battle decisively in favor of the PVN.
In the two years following, the Terrans were only successful in destroying two additional Typhon destroyers.