|Out of universe information|
- "Remember - short, steady bursts."
Under the instruction of Col. Everett, he ordered two lieutenants to begin deploying RG/BBT SG military mounted gun platforms around the city in preparation for the attack.
Later, he attended a briefing, during which time he presented a plan to deploy space mines using Puddle Jumpers in a pattern between the approaching Wraith fleet and Atlantis. He furthermore informed the group about the power-generating capabilities of the Mark II Naquadah generator, stating it can achieve up to 600% of the Mark I's output for a limited time.
When the first wave of Wraith darts began their attack on the city, Radner instructed his marines to fire in short, steady bursts at the approaching ships. As the engagement progressed, he radioed Col. Everett, informing him that several darts had begun to make kamikaze runs on the city. During this time, Radner stood as a RG/BBT SG military mounted gun helmsman.
Later, after the first wave had been successfully repelled, Rander and Ford prepared the Genii nuclear weapons that Dr. Mckay had finished working on for transport. Radner, followed by Zelenka and several marines, then transported the bombs to the jumper bay to load them onboard.
During the second wave of darts that attacked the city, Radner was part of Lt. Ford's group. He, as part of Ford's group, was attacked by a group of Wraith during the battle who beamed in on the group's position, surrounding them. During the ensuing firefight, Radner was thrown by a Wraith. It is unknown if he survived the engagement. Chuck later notes that he lost contact with Radner, Ford and Teyla, indicating that Radner may have ultimately been killed. (SGA: "The Siege, Part 2", "The Siege, Part 3")