UNSC Gettysburg

The  was a Frigate in service with the UNSC Navy during the Human-Covenant War.

Sigma Octanus IV
On July 17, 2552, the Gettysburg, along with the, responded to a distress signal sent by Commander Jacob Keyes from the Sigma Octanus System. The vessel later fought in the Battle of Sigma Octanus IV.

The vessel then returned to the orbital space dock of Reach, where it was heavily damaged in the Battle of Reach. There the entire crew was killed in the battle.

Gettysburg-Ascendant Justice
Eventually, SPARTAN-117, along with several survivors of Battle of Installation 04 and Battle of Reach, used the Gettysburg, fusing it with the Covenant ship Ascendant Justice, thus becoming the first Human-Covenant hybrid vessel in history. It was used because the Ascendant Justice could not do the two Slipspace jumps in and out of a group of Covenant ships fast enough using just it's own reactor.

Operation: FIRST STRIKE
Eventually, the vessel was unlinked from the Ascendant Justice so that Vice Admiral Danforth Whitcomb and First Lieutenant Elias Haverson could use the Ascendant Justice to lure a Covenant battle fleet to the Unyielding Hierophant, which was about to explode.

Return to Sol
After Operation: First Strike, the Gettysburg and it's extremely small amount of remaining crew headed back to the Sol System, Earth's home system.

It is unknown what happened after this, as it was probably scrapped for it's metal to make weapons, vehicles, and warships for the crumbling UNSC Defence Force. Possibly, it could've been reassigned to the UNSC Home Fleet just in time for the defense of Earth during the First Battle of Earth. However, the Gettysburg was heavily damaged and crippled, and the time it would take to refit the ship wasn't available to the Home Fleet. It is also highly likely that the Gettysburg was studied to design more advanced weapons or other systems based on Covenant design

Technology
The Gettysburg was refitted with the slipspace engines from the Ascendant Justice prior to unlinking. Since Covenant Slipspace engines had always been faster than UNSC engines, the Gettysburg then became fastest ship in any of the Fleets of the UNSC Navy.

Trivia

 * It is named after the Battle of Gettysburg. The American Civil War battle took place on July 1-3 1863, in Gettysburg, Pennsylvania, on Earth.