The Gauntlet is an special mission featured in Ace Combat Zero: The Belkan War. This bonus mission is unlocked by destroying all target ace squadrons (from all ace styles).
The Gauntlet takes place in Airspace B7R, the "Round Table". In this mission, players will face a series of enemy ace squadrons from the main storyline. However, said aces will depend on how fast the player shoots down the only default encounters which are those with the Gelb and Espada Squadrons.
The Ace squadrons faced here are dependent on how long it takes you to shoot down Gelb and Espada Squadrons. In one minute or less, you will face off against the Mercenary Aces. 2 minutes will pit you against the Soldier style Aces, and over 3 minutes will pit you against the Knight Aces.
The BGM for this mission is the game's title overture, Zero.
The player has the opportunity to engage in a one-on-one showdown with Ace Combat 04: Shattered Skies's Mobius One if the appropriate conditions are met. In order to engage Mobius One, the player must engage & destroy the Espada Squadron under one minute in Ace difficulty. Afterwards, the Wizard Squadron will spawn & head towards the player, with a single, unknown target following behind. Said aircraft eliminates all Wizard aircraft with a missile salvo in seconds—this aircraft is an F-22A marked "Mobius".
Mobius One stands out from other ace pilots thanks to his combat AI: he can launch 4-missile barrages, pull 90° high-G turns and fire missiles backwards. In addition, he takes an impressive four missiles to take down. This, combined with his penchant for evading missiles makes him one of, if not the, toughest Ace pilot to take down in the game and possibly the series so far(along with Milosz Sulejmani and Andrei Markov).
The annihilation of Mobius (a feat in itself) alone will net the player with a 30,000 credit reward.