In the early years of the Earth Alliance/United Tau'ri Alliance treaty, the Terran Govenment and Earth Force R&D agreed on a technological exchange. As part of this Technological Exchange, Earth Force R&D bought several decommisioned ships back into active service and several of these vessels were gifted to the United Terran Military.
These gifted vessels were quickly overhauled by the Earth Alliance with Terran supervision, so that they could be used by the United Terran Military straight away. At this time, the war with the Wraith had slowly escalated and the Wraith known as Todd had been gaining more support. He was now leading an attempt to regain the Pegasus Galaxy from the Terrans. These upgraded vessels were instrumental in holding back the Wraith advance.
One ship gifted to the United Tau'ri Alliance was the Avenger-class Heavy Carrier 'Eclipse'. This ship, like many others, was completely overhauled with help from the main Earth Force shipyard over Mars and refitted with advanced Terran technology.
Some of the upgrades included the replacement of the large hanger bays of the Eclipse in favor of Drone storage bays. While the ship retained only two of the ventral bays that were remodeled for F-302's and Jumpers. The weapons, power generators and computer systems were also replaced with superior Asgard technology. The Eclipse (when complete) was then sent straight to Pegasus to act as the main base of operations with it's own stargate for resupply.
The Eclipse itself was instrimental in defending many worlds from the renewed Wraith advance and played a pivitol role in battles where the odds were against the Terran ship. This mammoth took part in operations, Genii Defence and Traveler Protection, that are famed as the greatest moments in Terran space history.
While these ships were outdated, they still managed to fight with the best Terran ships until they were replaced by Terran-built versions.