The USS Thagard was constructed and launched from the Thuruthelf Shipyards orbiting Andor. It completed trials on Stardate 9585.02 and was comissioned to the Seventh Fleet on Stardate 9622.1.

On 9845 all contact is lost with the archeological research team dispatched to the planet Thalim. USS Thagard is assigned to escort a replacement team. The planet is known by many names in the ancient records of neighboring star systems, but the most common is Phaester Osiris, home world of a dead race known as the Osirons. No trace of the original archeology team was discovered. Thagard captain and crew logs report an increase in shipboard tension and odd feelings of being watched. Two days after entering orbit the Thagard dispatches two shuttlecraft to the planet’s surface. A base camp and a direct beam sensor link are established.

Scholars differ in their opinions of the Thalim discoveries. Evidence indicates a humanoid race once inhabited the planet. Some contend that the pictographic and architectural evidence found bears a striking resemblance to a dozen other younger cultures, including that of Ancient Egypt on Earth.

Captain’s Personal Log Entry: "Chief Engineer can not explain the continuous system problems that have plagued us since our arrival. Yesterday the direct beam link to the base camp was severed for nearly three hours. Entire crew tense. I myself am experiencing dreams, nightmares, featuring those damn Tolyek masks they found at the temple dig sight. I have ordered over a dozen life scans, including a subsurface drill probe… the planet is dead."

Three members of the scientific team are killed when they enter the newly opened burial tomb at site three. High-energy emissions from hidden sources within the rock are the cause – an ancient booby trap left by the final inhabitants. Rescue workers report hallucinations consisting of visions featuring the elongated facemasks common on the tomb walls.

Tragedy strikes on day 21 of the mission. To support deep scan activities, the Thagard’s main sensor array is trained on a designated spot at campsite 2. When the direct beam is re-engaged, a massive feedback pulse is transferred up from the planet’s surface. The brilliant beam of light and energy overloads several key systems. Five crewmembers are badly injured and the ship’s orbit destabilizes. Recovery efforts succeed in saving the ship, but the damage is too severe to continue the mission. The Thagard returns to Starbase 55.

A hearing into the events of the second Thalim mission determined that the captain and crew were not to blame for the mishaps. The Captain and Chief Engineer were each issued commendation for the successful recovery of the badly damaged Thagard. Despite being exonerated of any blame, the Captain and several members of the crew resigned from Starfleet shortly after this mission. Repeated nightmares were sited by many of these individuals. The Captain has never come forward with his reasons.

The starship Aurora is dispatched to Thalim shortly after Expedition 2 is abandoned. After disaster befalls this mission the planet is closed to further official investigation.

The Romulans have repeatedly tested Federation resolve by crossing the Neutral Zone in one or two ship incursions. Shortly after the Thagard is returned to active duty she passes near the Tomed sector when twelve Romulan warbirds invade the disputed area. Warnings from the Harrison Outpost and the Thagard are dispatched and 7th Fleet is quickly assembled. The Thagard soon finds itself being pursued by a Romulan Whitewind class cruiser. Both ships have equal speed and maneuverability, but the Federation Science Vessel has virtually no offensive capabilities. The Thagard passes through the rings of Planet 936-E and uses the main deflector to cast "ghost images" to confuse the Romulan vessel. This delaying tactic provides her enough time to hold out until a twenty-ship Federation taskforce arrives.

Thagard takes up a rearguard position, using her sensor equipment to relay telltale clues about the cloaked Romulan vessels. The Starship Radetsky, positioned a thousand kilometers to port of the Thagard, is hit dead on by a photon torpedo. The ship explodes, damaging the Thagard and crippling her sensor capability. In one of the lucky fortunes of war, the Thagard manages to fire her single phaser bank at the Romulan vessel that had destroyed the Radetsky. The shot destroys the enemy’s cloaking generator, allowing the ship to be easily picked off by Federation warships

Many fine Starfleet vessels are lost that day, including Radetsky, Thurlefth, and Star of Izar. When the Romulans finally withdraw the Thagard is one of the vessels that participate in the search for survivors.

Stardate 9905.12 is a unique and monumental event for the USS Thagard. In a symbolic gesture to emphasize Starfleet’s commitment to scientific research, the Thagard is named honorary flagship of the fleet and the Admiral’s Flag is conveyed to her. Though no actual Fleetwide command and control functions are transferred to the Thagard, a major refit, scheduled four years earlier, but never completed, is finally performed. Updated scientific equipment and the construction of an amphitheater for presenting new findings are added.

Following her one-year parade tour, Thagard participates in another first. Her crew is vastly expanded and she is assigned to Deep Explorer Station 1. The DES program anticipates the more ambitions Deep Space (DS) stations that will follow. Thagard’s crew and scientific compliment are increased to 100 personnel. A small marine unit, the 701st, is assigned to her in support of missions on dangerous planets. Together with her DES support base, Thagard is assigned semi-permanent duty at Oran Dreti on the edge of known space.