- This article is about an in-universe event. For the in-game mission, see Sitting Duck.
- "...with the Allied Forces facing their most perilous hour, [Mobius 1 and his allies] were seen as little more than a shot in the dark - a desperate attempt to postpone defeat. In retrospect, however, it was the start of a tremendous rebellion."
- ― F-4E -Mobius1- description
Operation Umbrella was an Independent State Allied Forces defensive operation in the middle of the Second Usean Continental War. On the brink of victory, Erusea deployed a bomber squadron to destroy ISAF's last remaining bases, prompting the ISAF to launch some of its remaining fighters to intercept the bombers. The fighters were victorious, granting ISAF some breathing room to begin attempting counterattacks.
This was the first known operation in which Mobius 1 took part. The pilot would later become ISAF's top ace, whose actions would lead ISAF through a number of critical victories and a year-long counterattack which ended the war one year later.
After the failure of the Stonehenge assault, the ISAF lost important strongholds throughout the mainland due to its inability to maintain air superiority within Stonehenge's attack range. After ISAF evacuated to North Point and established a new GHQ there, the Federal Republic of Erusea deployed bombers to nearby Rigley Air Base, a former ISAF airfield, to destroy Allenfort Air Base and the GHQ, finishing the war.
Erusian agents destroyed ISAF's early warning radar system, allowing a squadron of six Tu-95 Bear bombers from Rigley Air Base to slip past ISAF's remaining defenses. Escorted by several Erusian fighters, the bombers were intercepted and engaged by the ISAF's remaining squadrons. One of these squadrons was the 118th Tactical Fighter Wing (Mobius Squadron), which consisted solely of Mobius 1 at the time.
By the time ISAF fighters, directed by AWACS SkyEye, had reached the airspace, the Erusian bombers were already over Newfield City. Surprisingly, Mobius 1 took the lead and began to shoot down the bombers. Other ISAF fighters, with Mobius 1's help whenever possible, engaged the bombers' escorts. The remaining bombers reached Allenfort's airspace and began dropping their payloads, but it wasn't long before Mobius 1 shot them down as well. Allenfort confirmed the bombers' destruction and thanked the pilot.
Although Newfield City and Allenfort Air Base were damaged, no permanent damage was incurred, and the base resumed operations soon after. This operation may have been minor in terms of scope and the number of combatants, but it gave ISAF's troops a much-needed morale boost to show Erusea that they would not surrender without a fight. Mobius 1 also received some recognition from the commanders of Allenfort for protecting the base.
Since the bomber squadron was only a detachment of the overall force that was still stationed at Rigley Air Base, ISAF needed to destroy the remaining Erusian bombers to prevent another attack.