Sometime in 2007, an undercover operative within the Lucian Alliance gave the location of P4X-351 to the Tau'ri. Shortly after, the Tau'ri attacked the mining camp on the planet and forced the occupants to evacuate, allowing the Tau'ri to set up Icarus Base as a staging ground to dial the ninth chevron of the Stargate. After two years of failed attempts, Eli Wallace developed an equation which was believed to be the key to successfully dialing the ninth chevron. He was recruited by Lt. General Jack O'Neill and Dr. Nicholas Rush to view the results of his work. He was transported to the planet via the George Hammond, along with Senator Alan Armstrong and his daughter, Chloe Armstrong. His equation was put to the test but failed to achieve a lock. (SGU: "Air, Part 1")
BattleEditIcarus Base was attacked by a force of three Ha'tak motherships, Death Gliders, and Troop transports. They opened fire the moment they dropped out of hyperspace. This prompted an evacuation. In the ensuing battle, Colonel David Telford engaged the attacking forces in an F-302 fighter-interceptor. In desperation, Dr. Nicholas Rush, with the help of Eli Wallace, figured out how to dial the nine-chevron address and dialed it instead of Earth, forcing those who were still on the base to evacuate to the Ancient starship Destiny. Colonel Everett Young, the last to leave, was thrown through the wormhole by the explosion and badly injured.
When the base came under attack, the core of the planet destabilized, resulting in the complete destruction of the planet. The attacking Ha'tak vessels were destroyed, as were all their ground forces. The George Hammond anticipated the explosion and escaped to hyperspace in time, having managed to locate all but approximately 80 of the Icarus Base personnel and evacuate before departure. (SGU: "Air, Part 1")
Colonel Samantha Carter, commander of the George Hammond, reported that the remaining personnel who could not be accounted for were inside the base and could not be beamed out; however, readings indicated that the Stargate was active for six minutes before the planet's core went critical, so it was assumed they went somewhere. Dr. Nicholas Rush later reported to Homeworld Command from Destiny via the Long-range communication device, informing Lt. General Jack O'Neill of their situation.
Unbeknownst to the Tau'ri, the Lucian Alliance was responsible for the attack. Having failed to recapture the planet, they instead devoted their efforts to recreating the conditions that allowed Icarus Base to dial Destiny, in the hopes of seizing it for themselves. Commander Kiva setup a research base on a planet similar to P4X-351, where they duplicated the Icarus project's research. However, they lacked the equation to regulate the power, thus stalling their progress. Eventually, they captured Rush in Colonel David Telford's body and forced him to help finish it before an attack by the George Hammond forced the Alliance to dial early, causing that planet to explode as well, but not before some of the Alliance forces finally made it to Destiny. (SGU: "Air, Part 1", "Air, Part 2", "Subversion", "Incursion, Part 1")