- This article is about an in-universe event. For the in-game mission, see Stonehenge Defensive.
As Osean forces proceeded to liberate the Usean continent, the western part of the continent, as well as the International Space Elevator, remained under Erusean control. The Arsenal Birds made it difficult for any advancements towards the region. As a result, the Osean Army began secretly repairing the last remaining Stonehenge railgun, which was left untouched after the ISAF's bombardment over the area, and reactivated its base systems, all with the intent of shooting down one of the Arsenal Birds.
Defensive positions, codenamed "Menhirs", were set up around the railgun network.
During the battle, the Cyclops and Strider Squadrons were tasked with defending the railgun and the Menhirs in the area. As the battle progressed, Erusea deployed several ground forces, fighters, bombers, artillery units and helicopters. During the battle, an Erusean agent infiltrated the railgun network, killing various guards and civilians operating as survey technicians. The Cyclops and Strider Squadrons successfully defended the railgun from enemy attacks.
Following the defense of the railgun, the Arsenal Bird Liberty entered the airspace and deployed its drones. Due to the survey team's demise, the team operating the railgun were forced to aim it visually. The Cyclops and Strider Squadrons assisted in defending the railgun from drone attacks, while Trigger and Wiseman destroyed Liberty's main propellers in order to slow it down. The Arsenal Bird soon hastily deployed its APS to prevent further attacks and as a last ditch effort to protect itself from Stonehenge, sacrificing a few of its drones caught within the shield's range in the process.
With the Arsenal Bird slowed down, the railgun was fired, penetrating its APS and destroying Liberty, crashing near the railgun network.
Upon firing, the railgun broke down, rendering the entirety of the Stonehenge railgun network inoperable. With Liberty's destruction, the Arsenal Bird's defense network was significantly reduced, now only covering the Gunther Bay area.