- "The only way to destroy this highly dangerous and fortified facility is to hit it from the inside ... Remember, we need heroes after the war too. Make it back in one piece."
- ― ISAF briefing officer
Megalith was a missile-launch facility built on the Twinkle Islands by Erusea in the early 21st century. It was created in secret and immediately activated following Erusea's defeat in the Continental War as a retaliatory weapon of mass destruction. The facility was subsequently destroyed by the ISAF's Mobius Squadron and its ace, Mobius 1.
Erusean engineers began working on Megalith by sometime in the 2000s. It is unknown if the concept existed prior to the Continental War, but the facility was well under construction following Stonehenge's destruction.
In May 2005, an ISAF spy plane, callsign "Leopard", obtained photographic evidence of the construction efforts, prompting the ISAF to bolster its own efforts in defeating Erusea before Megalith could be completed. The ISAF was ultimately successful: Erusea was unable to employ Megalith before its capital, Farbanti, fell to the ISAF in September.
Activation and destruction
One week after Erusea's surrender, a group of young officers took over Megalith with the intention of using it against ISAF in retaliation for their country's defeat. On September 26, ISAF dispatched a special forces team (led by Bravo 1) and the newly formed Mobius Squadron (under the command of Mobius 1) to destroy the facility. The Erusean forces responded by launching a defense squadron to intercept Mobius Squadron.
Despite the Erusean officers' fierce attempts to hold them back, as well as heavy casualties on both sides, ISAF slowly overpowered the Eruseans. Bravo 1's ground unit held positions in the facility while Mobius 1 destroyed three main generators from inside Megalith's access tunnels. The resulting blackout allowed the special forces to assume control of the sub-control room and open the central heat vent. Mobius 1 flew into the opening and destroyed the large ICBM stored within. After he escaped using another set of panels opened by the ground forces, the warhead's detonation triggered an explosive chain-reaction within Megalith, rendering it inoperable.
Megalith was a massive facility that encompassed several hundred square kilometers. Most of its systems were operated from a sub-control room located on the 13th floor of the structure. The facility's main missile port grooves were armed with multiple ICBM silos and laser targeting systems, which "painted" the desired asteroid(s). Several tunnel openings—located along Megalith's north-south and east-west axes—led to the generators that powered many of its critical systems. The facility also contained four large missile launchers, as well as a fifth, even larger central silo; these launchers had the capacity to fire more powerful ICBMs.
It is possible that Megalith could also have been used to launch ICBMs directly at targets anywhere within its operational range. However, the facility's ability to redirect Ulysses fragments was ultimately used to turn asteroids into kinetic weapons, forcing them to descend from orbit and cause tremendous damage across a large target area.
- Megalith's function as a weapon—using asteroids to impact areas on the planet—was re-introduced as the function of the OLDS, the main superweapon in Ace Combat Infinity.
- Megalith's name comes from the word "megalith", which is a large stone used to build a structure or monument.
- The term is typically used to refer to tombs constructed in this way, particularly in Europe, as well as for sacrificial ceremonies. Both have symbolic meaning to the nature of Megalith's destruction; numerous ISAF and Erusean soldiers died in the fight, and Mobius 1 (symbolically) sacrificed his life to destroy the large missile.
- Stonehenge, the namesake of the Erusean superweapon, is considered to be the most popular European megalith.
- Megalith is likely the most powerful superweapon in the Ace Combat series, due to its long range, high ammunition count, and potential for space combat.
- From above, particularly at the end of the mission intro cutscene, Megalith strongly resembles a cross, or crucifix.
- Megalith bears an uncanny resemblance to Fortress Intolerance, the facility featured at the end of Ace Combat 2 and Ace Combat: Assault Horizon Legacy.
- This can linked to the way both were destroyed and, in the case of Ace Combat 2, the way the heat vent walls were modeled: both use similar texture files to render the walls of the tunnels but the Assault Horizon Legacy and its re-release version of Intolerance feature a more updated texture.
- The mission briefing graphic in Ace Combat 04: Shattered Skies includes a projection of possible asteroid fragment impacts in northern Erusea (two), northern Usea (two), North Point, archipelago west of Tyler Island, Los Canas and in the Usean oceans.
- During the briefing for the Ace Combat 7: Skies Unknown mission Homeward, Megalith makes a cameo appearance on the map as Strider is considering possible relocation options; Lanza appears to briefly consider the location as a possible base, but ultimately moves on to Tyler Island.