- "Galactica is not a relic, it's a classic. And I for one happen to appreciate the classics."
- Admiral Helena Cain
Galactica was an early example of a fleet carrier classification known as a Battlestar. Battlestar Galactica was constructed at the beginning of the First Cylon War, and saw considerable service during the twelve-year conflict. Designed to be operated through non-networked computers, the Galactica and the other eleven in its class were therefore immune to Cylon hacking methods. Despite some twenty years of military rearmament, radically increased under the Adar administration, Galactica continued its service in the Colonial Fleet for forty years until its decommission.The ceremony preceded a massive Cylon strike on the Cyrannus star system, destroying 118 other Battlestars within hours due to the Colonial Fleet's return to networking. For the next four years Galactica and, briefly, the Battlestar Pegasus, journeyed with a ragtag fleet of civilian ships in search of Earth, suffering horrendous damage with no opportunity to repair it. Though Earth was found to be a nuclear wasteland, the fleet kept on in search of another home and, once discovered, Galactica and the fleet were piloted into the planet's star as a final decommissioning.
At the start of the Cylon uprising, the Twelve Worlds which made up the loosely-defined Colonial Government agreed to surrender the bulk of their sovereignty into a single state known as the United Colonies of Kobol. Now with a single military defending all worlds rather than militaries and militias of various sizes defending their homes, the Colonial Fleet stood a greater chance in coordinating a counteroffensive. In the spirit of the alliance, twelve Battlestar carriers were constructed, representing the twelve sovereign worlds. Galactica represented the planet Caprica, though its military role was not to defend it.
On the twelfth year of the war, Galactica took part in Operation: Raptor Talon, an attack with Battlestar Columbia on a Cylon flotilla defending a planet of critical importance to the war owing to rumours of a Cylon weapon being constructed there. Columbia was destroyed, though the battle was left indecisive as the Cylons signed an armistice agreement with the government mid-battle.
- During the First Cylon War (which takes place before the events of the new series), Galactica was built to represent the Caprica colony. She was built without networked computers to avoid being hacked by the Cylons
- During the 10th year of the Cylon war, rookie (fresh meat) William Adama comes aboard the Galactica. After Lt. Adama's first mission and rescue the Galactica and the Ghost Fleet launched a new offensive.
- During the First Cylon War, Galactica along with the Columbia and one other unnamed Battlestar took part in Operation Raptor Talon; where the Columbia is destroyed with all hands.
- Many years after the war, Galactica was one of the oldest ships in the fleet, and was scheduled to be decommissioned and turned into a museum. Various conversions were taking place and most of her onboard squadrons were removed.
- During the decommissioning ceremony, the cylon attacks on the colonies began. After a battle, including many direct strikes, Galactica successfully jumped away to the Ragnar Anchorage depot.
- Galactica then leads and defends a small fleet of civilian ships on the search for resources and a new place to settle.