First siege of Atlantis

The First Siege of Atlantis was the last battle in the Lantean-Wraith war that occured 10,000 years ago.

Prelude
In the later stages of the Ancients century long war with the Wraith, after destroying the Ancient's Colony cities, like the one on Athos with a fleet augmented by the army created at the cloning facility, there was little between them and Atlantis.

The Battle
The assault began with the Lantean defense satellites located around Lantea's system boarders, as the organic fleet exited hyperspace, they met quick destruction from afar when the Lantean Satellite crews, under the command of High Councillor Moros from Atlantis, began to target and destroy the Wraith ships that entered in-system.

The First Siege of Atlantis had begun.

While the stout determination of the Lanteans' and their powerful technology kept the numerous and aggressive foes at bay for the beginning of the attack, the Wraith brought in greater numbers and began extreme acts of relentless assaults. Such as ordering their Dart pilots to commit to kamikaze charges against the Defenses of Atlantis and massive barrages of Hive and Cruiser weapons fire, obliterating all in their path. Eventually, the Wraith managed to destroy all of Lantea’s outer system defense satellites, minus one Satellite which they disabled and left alone. Making their way inward, they flew their ships into Lantea's orbit as well as Atlantis' weapons range upon which the City-Ship’s drones destroyed all but one which was damaged and left to crash into the planet's ocean.

However effective the Lanteans were at destroying individual ships, the whole of the Wraith fleet continued to field as many ships as possible into Atlantis' orbit in order to finish of their weakening adversaries. Seeing no way to win the war, yet still capable of dealing tremendous damage, the Lanteans' send a delegation under the protection from some of their most powerful warships still remaining from the long years of war in the hopes of negotiating a truce. This was not the case, for the aggressive Wraith were empowered by the knowledge that they were on the edge of winning the war and making the galaxy their own with it's renewable stock of Human herds to consume. The Wraith, ignoring how much of their numbers would be destroyed, attacked the delegation, destroying it as well as the Lanteans' only means of effectively continuing the conflict. The Lantean-Wraith war had been lost.

Aftermath
As Atlantis was only armed with Gate Ships and only a few dozen Drones, the Lanteans saw no way to continue fighting as very little remained of what was once part of their great civilization to give them the means to defeat the Wraith. With only one facility (Atlantis) remaining, they saw no way to produce enough drones to replenish any ships left or to repair those that were inoperational. With the Wraith everywhere in the galaxy, the Lantean Council recalled every surviving Lantean back to Atlantis for the evacuation. With the main force of the Wraith fleet hovering over Atlantis ready to unleashed a massive bombardment upon the city if it ever surfaced, the once great capital of the Ancient Domain was trapped at the bottom of Lantea's ocean. Facilitating the only way for anyone left of the war to survive, the Lantean council decided to evacuate everyone through the Stargate to Earth. In the Hopes of returning to Atlantis in later generations.

It is possible that they had hoped to return with reinforcements from their brethren that might still be alive in the Milky Way, or possibly enlist the help of the Humans from Earth, whom they left behind, to help them rebuild their civilization. Whatever the case was, when they returned to Earth, to their surprise, all they found were tribes of spear wielding hunters living in an environment too harsh to rebuild the Ancients' civilization. Instead, they decided to lay the seed for which the future descendants might use. Several interbred with man in order to pass on the ATA gene and help create the earliest civilizations. Some went on to seek Ascension, while others likely helped to forge the Alliance of Four Great Races.