After the conclusion of the continental war, the ISAF's coalition forces occupied Erusea to maintain order and oversee the nation's reconstruction efforts. The ISAF observers also helped the Eruseans establish a new interim government that aimed to replace Erusea's militaristic ideals with more peaceful, cooperative ones. Although most of the Erusean military, having suffered tremendously during the final months of the war, welcomed the regime change, many military officers and personnel began expressing their disillusionment with the interim government's pacifism. From their perspective, ISAF was corrupting Erusea's proud heritage and asserting foreign ideals on their fellow countrymen.
Sometime in 2006, the dissatisfied Eruseans, led by a group of high-ranking Federal Erusea Air Force officers, managed to capture a dilapidated IUN weapons factory in White Valley Bay. The rebels, now calling themselves "Free Erusea," denounced ISAF's interference and began using the factory as their base of operations to launch an insurrection against the interim government and ISAF observers.
Soon after its declaration of war, Free Erusea began to attack ISAF at various locations across Erusea and the rest of the Usean continent. To address this new threat, ISAF dispatched a small force comprised of an E-767 AWACS, callsign SkyEye, and Mobius 1, the ISAF ace who almost single-handedly turned the tide of the continental war in ISAF's favor. ISAF command selected Mobius 1 for this operation due to the fact that his mission execution capability alone was found to be equal to that of an entire ISAF Air Force squadron.
Although it did not possess a strong ground force, Free Erusea relied on transport aircraft and ships to support its operations. Free Erusea did, however, possess an extensive supply of fighter aircraft—many of the Free Erusea rebels were FEAF pilots who had defected with their planes—and a sizable naval fleet, which included at least one aircraft carrier. Despite being numerous and widespread, the Free Erusea forces were quickly outmatched by Mobius 1's prowess and began falling back to their headquarters in White Valley.
As the final engagement unfolded, Mobius 1 attacked the rebels' base and successfully destroyed the remaining Free Erusea forces. However, a squadron of experimental X-02 Wyverns, which had been under development and later abandoned during the war, engaged Mobius 1 in a final attempt to shoot down ISAF's ace. Despite the Wyverns' superior avionics, Mobius 1 outmaneuvered and dispatched the remaining hostile fighters, effectively ending Free Erusea's rebellion.
Soon after Mobius 1's decisive victory, ISAF ground forces raided the base and took Free Erusea's core members into custody. The ISAF also recovered data on the Eruseans' unmanned fighter aircraft program, which had long been veiled in secrecy. With the uprising quelled, the new provisional government was successfully established, and Erusea finally began its path to recovery.
Following the Circum-Pacific War in 2010, the world's military forces became severely weakened. Free Erusea took advantage of the situation and used it to build up their strength, becoming a global threat. In 2014, Mobius Squadron, now under the command of the IUN, was deployed to quell the insurrection. Over the course of six weeks, Free Erusean forces were defeated. After the conflict ended, their efforts were revealed to be a diversion and their true objective remained ambiguous.
During the Lighthouse War in 2019, Free Erusea opposed several factions that had splintered from Erusea following the destruction of Usea's satellite network. At the end of the war in December 2019, they continued operations in northern Erusea.
- Red Squadron
- Blue Squadron
- Black Squadron
- White Squadron
- AV-8B Harrier II plus
- F-15C Eagle
- F-16C Fighting Falcon
- F-22A Raptor
- MiG-21bis Fishbed
- MiG-29A Fulcrum
- MiG-31 Foxhound
- Mirage 2000
- Mirage 2000-5
- Su-30M2 Flanker-F2
- Su-35S Flanker-E
- Su-37 Terminator
- X-02 Wyvern
- Suribachi-class container ship
- Anchorage-class landing ship
- Nimitz-class aircraft carrier
- Pegasus-class hydrofoil
- Air Defense Tank
- Armored personnel carrier
- Anti-air gun
- Rocket launcher truck
- Surface-to-Air Missile
- In Ace Combat 04: Shattered Skies, the liveries of each enemy ace feature the Free Erusea emblem. This could hint at the group's existence before the end of the Continental War.
- Arcade Mode, Ace Combat 5: The Unsung War.
- VR Mode, Ace Combat 7: Skies Unknown. Cite error: Invalid
<ref>tag; name "AC7-VR" defined multiple times with different content
- Last Hope, Ace Combat 7: Skies Unknown.
- Ace Combat 04: Shattered Skies.
- Prologue, VR Mode, Ace Combat 7: Skies Unknown
- Mission 16: "Last Hope", Ace Combat 7: Skies Unknown.
- Cutscene 16: "The New System", Ace Combat 7: Skies Unknown.