Battle to save Atlantis

The Battle to save Atlantis was a number of engagements between the Tau'ri and Asurans, which took place in Pegasus galaxy in 2007.

Prelude
After the destruction of the Asurans during their takeover of Atlantis, the Daedalus was sent to periodically fly over the Asuran homeworld and check things out. The Daedalus discovered that the Asurans were building a fleet of ships to attack either Atlantis or Earth. In response to this, a plan was devised, on Earth, to stop them.

First strike on the Asurans
The Apollo's' first mission was to fly to Atlantis to use the new Horizon weapons platform in a first strike to destroy the Asuran's new ships. Col. Abraham Ellis assigned Drs. McKay and Zelenka to prepare the Horizon, consisting of ten Nuclear warheads, for deployment. The Apollo existed hyperspace very close to the planet, and launched Horizon. The ten warheads were able to obliterate all the ship-building facilities.

However, in retaliation, Oberoth launched a Stargate satellite to over Lantea, and started to attack Atlantis. Because of the strength of the beam emanating from the satellite, Atlantis' shield would be depleted in a matter of days and the city would be destroyed. So, the Expedition planned to submerge the city to allow the water to attenuate the beam intensity. However, the water did not stop the beam, it only slowed it down. Eventually, Rodney McKay and John Sheppard were able to devise a way for Atlantis to evacuate Lantea and fly to M12-578 through Hyperspace by engaing the city's stardrive. To enact this plan, a squadron of F-302s was sent to pull a large asteroid from the system to block the beam, which allowed Atlantis to lower its shield, activate the Stardrive, and leave the planet. However, the beam grazed the central control tower before the shield could re-close completely. Because of this, the city exited hyperspace far to early in the middle of nowhere, with only 24 hours of power left.

Atlantis Adrift and ZPM raid
With Atlantis adrift in space, the city was very low on power. In order for Atlantis to reach its new home planet, the Expedition needed to obtain a ZPM and, as the only known ZPM's are on Asuras, they came up with a plan. Using a hyperdrive generator prototype developed by Rodney Mckay equipped on a Puddle Jumper, they were able to reach the planet, using up a lot of power in the process.

They descended onto the planet and landed on top of a building housing a ZPM hub. In order to prevent capture, Dr. Weir, and her reactivated replicator nanites, guided Sheppard and Ronon to the ZPM, avoiding an encounter with a replicator on the way.

The mission was successful, however, McKay discovered a disabled line in the Asuran base code that would force them to attack the Wraith. However, the only way to reprogram them was to update their computer core manually. Risking everything, Sheppard and Ronon went back into the city. They formed an anti-Replicator field around the core, using the Jumpers cloaking field, to buy them some time and began trying to reactivate the code. Unfortunately, the process took too long and the Replicators managed to counter the field. With hundreds of Replicators heading towards the core, Dr. Weir left the jumper in an attempt to stop them. Ignorant of her true purpose, McKay attempted to disable the nanites and kill her, but the command failed to work.

She confronted Oberoth and made physical contact with him, connecting herself to the Replicator network. She used her access to freeze all of the Replicators and fool Oberoth into thinking he had captured the team to give them time to escape. Sheppard, not wanting to leave Weir behind, went to search for her. However, Oberoth began to resist her control over the network and managed to physically grab her arm. She pleaded for Sheppard to run and leave her behind. Sheppard was forced to run back to the Jumper and escape without her.

Escape from Asuras
Frantically trying to interface the ZPM with the jumper in order to open a hyperspace window, an Asuran warship appeared in front of them. Fortunately, they were saved when the Apollo arrived, weapons firing, having found Atlantis and came to help once they learned of the team's plan. The Apollo distracted the Asuran warship pursuing them long enough for the Jumper to land in one of the 302 Bays and then jumped to hyperspace without either ship suffering any major damage.

Aftermath
Back in Atlantis, they were able to install the ZPM, and the city became fully powered. McKay found them a new home planet, M35-117, a planet with a large ocean, like Lantea. He purposely left out a group of planets during earlier considerations, so the Asurans could probe Weir's mind and still never find Atlantis. The city jumped into hyperspace, and arrived over M35-117. Sheppard then went into the Control chair, where he could pilot and land the city. After a rough re-entery, Atlantis landed safly in the ocean with plenty of power remaining in the new ZPM. Atlantis would remain on it's new planet until 2009.