Atlantis expedition
From The Stargate Omnipedia
A mission petitioned by Dr. Elizabeth Weir to General Jack O'Neill and President Henry Hayes, culminating the cooperation of over a dozen countries and including some of the world's finest minds.
After Daniel Jackson found the gate address to the lost city of the Ancients at the Antarctic outpost of Atlantus, Weir led the expedition through the Stargate to the distant Pegasus Galaxy.
KEY EPISODES
Rising, Part 1 - Given the go-ahead to travel to the Pegasus Galaxy, the Atlantis expedition commences with the knowledge that they may never be able to return home.
The Return, Part 1 - The expedition comes to a surprising end when a group of Ancients return and reclaim their right to the city.