The Tau'ri-Genii conflict was a rivalry between the Tau'ri of the Atlantis expedition and the Genii in Pegasus galaxy. It began following a joint mission to infiltrate a Hive ship, wherein the Genii soldier Tyrus was lost, and ended after Ladon Radim successfully took power. Minor skirmishes, however, happened in the wake of Radim's coup.
First contact between the two races occurred during the Atlantis expedition's first year on Atlantis. Teyla Emmagan introduced the expedition to the Genii as potential trading partners, unaware of their true nature as a military power. When Dr. Rodney McKay and Major John Sheppard discovered their secret, a tentative alliance formed, as the expedition had supplies and technical expertise which the Genii lacked.
The two groups held a joint operation to raid a Wraith Hive ship for data concerning their fleet movements. During the raid, Tyrus was captured by the Wraith, having alerted them by killing a cocooned human who was making too much noise. Teyla was unable to save him, and thus Cowen, leader of the Genii, blamed her for his loss. He tried to force Sheppard to surrender his supplies and Puddle Jumper, but Sheppard had arranged for two more Jumpers to lie in wait, turning the tables on Cowen. He took the stolen Wraith data from Cowen as payment for the effort they expended on the mission, which Cowen took as an act of war. (SGA: "Underground")
Invasion of Atlantis
- Main article: Genii invasion of Atlantis
When a massive storm threatened to destroy Atlantis, the Genii were presented with an opportunity to raid the city for the necessary supplies to build their atomic weapons. Acastus Kolya lead a strike team into the city. Upon learning of the plan to save it, he enacted a much more ambitious plan to take the city for the Genii. His efforts were foiled by Sheppard and his team, and Kolya was shot in the shoulder while attempting to retreat with Dr. Elizabeth Weir as a hostage. Kolya declared Sheppard his personal enemy. (SGA: "The Storm", "The Eye")
Attempt to obtain ZPM
The expedition came close to discovering a Zero Point Module on Dagan, and this information was delivered to the Genii through their spy network. Cowen chose not to provoke them, but Acastus Kolya was more insistent, secretly leading a small team to steal the ZPM once the expedition had discovered it. He was again foiled by Major John Sheppard's team, and Sheppard warned him that he would not spare Kolya the next time. (SGA: "The Brotherhood")
Some time later, Ladon Radim, a member of the strike team that raided Atlantis, contacted the Atlantis expedition and offered to trade a Zero Point Module in exchange for their aid in overthrowing Cowen. He told them that Cowen intended to unite the entire galaxy under his rule, using his atomic weapons if necessary. The expedition decided to simply steal the ZPM rather than aid in the coup. Unfortunately, they discovered that it was a trap: the ZPM was depleted and they were taken hostage. Cowen and Radim had been working together the whole time. Having identified the members of the expedition who possessed the Ancient Technology Activation gene necessary to operate Puddle Jumpers, Radim was working on a way to artificially give the Genii the gene, while ransoming the hostages for Jumpers that could be used to deliver their weapons.
Radim, however, really was planning a coup, and the operation was the only way to draw Cowen into the open. Using a bomb planted underneath the facility, he killed both Cowen and his inner circle. The expedition hostages would have been left to die, but Radim freed them after learning that the Tau'ri possessed the means to cure the radiation poisoning many of his people suffered from. This marked the start of a stable alliance between the two powers. (SGA: "Coup D'etat")
Kolya's first attempt to seize power
After learning that Ladon Radim had deposed Cowen as leader of the Genii, Acastus Kolya believed Radim stolen what was rightfully his. Kolya was the first to suggest the idea of a coup, but Radim betrayed him, feeling him no more worthy of leadership than Cowen. After being driven into exile, Kolya and a small group of loyal Genii captured Lt. Colonel John Sheppard in an attempt to trade his life for Radim's. The expedition refused the trade, and Radim eventually managed to locate the world where Kolya was hiding. Sheppard was rescued, but Kolya escaped. (SGA: "Common Ground")
Kolya's second attempt to seize power
During an unrelated mission to investigate the claim that Lucius Lavin was a "superhero", Lt. Colonel John Sheppard once again came into contact with Acastus Kolya and his followers, who had been informed of Sheppard's presence by some Genii mercenaries cast out by Ladon Radim. Kolya captured Sheppard's team, minus Sheppard himself, and once again intended to ransom them in exchange for supplies for his coup. With Lucius' help, Sheppard and the villagers disarmed Kolya's men. Kolya himself refused to be captured, and was killed in an impromptu duel with Sheppard. (SGA: "Irresponsible")
Assassination of royalty
While escorting the queen-to-be Harmony to a shrine as part of her coronation ritual, Dr. Rodney McKay and Lt. Colonel John Sheppard was attacked by a group of Genii. The Genii were under the employ of Harmony's sister, Mardola. Though Harmony's people were resistant to trade with the Genii, Mardola would have been more open to it, but Harmony was next in line for the throne. McKay and Sheppard successfully protected Harmony, and Mardola was arrested. Radim claimed that this group of Genii were not acting under his orders. (SGA: "Harmony")
Coalition of Planets
When the Atlantis expedition was put on trial by the newly-formed Coalition of Planets, they quickly deduced that the Genii were bribing one of the judges to vote guilty so they would secure a position as the military power of the Coalition. Richard Woolsey convinced the judge that Atlantis was a better choice, being far more powerful than the Genii, allowing them to secure an innocent verdict. No word was given on Ladon Radim's involvement with this action. (SGA: "Inquisition")