P4A-771 was one of the earlier planets in the Milky Way galaxy that SG-1 visited in 1998. When SG-1 arrived, they came under fire from unknown attackers. The team was surrounded, so Dr. Daniel Jackson quickly dialed the gate to retreat back to Earth. Daniel and Teal'c made it through, but as Colonel Jack O'Neill and Captain Samantha Carter went through one of the alien's energy blasts hit the gate. This caused Daniel and Teal'c to be launched out of the gate at Stargate Command at such a force it rendered Daniel unconscious, and also caused a disruption in the Stargate which sent O'Neill and Carter to the second Stargate on Earth located in Antarctica.
While they were trapped there repairs were made on the SGC side and around a day later Major General George S. Hammond sent a MALP back to the planet but there was no sign of O'Neill or Carter and the MALP was quickly destroyed by the alien energy blasts. Due to this Hammond ordered they that would not attempt to return to the planet for a rescue mission. (SG1: "Solitudes")