"Aces" is the name given to the final mission in Ace Combat 5: The Unsung War. The mission is set after Pops discovers the secret behind the disk the "Major" brought with her.
It is revealed that the "Grey Men" have secured the long-lost Belkan V2, and are planning to use it to take out half of all the large cities in either Osea or Yuktobania. If so, it could cause major destruction on either country. Apparently, the "Grey Men" have put the V2 aboard the SOLG, where they plan to deploy it. It is also discovered that the SOLG is being controlled in a facility under Sudentor, an "experimental facility". In the facility, is actually a tunnel, which leads to the frozen wastelands of Belka. What is in the tunnel, however, is not found out yet, as it turns out that an enemy submarine is attacking the OFS Kestrel, which interrupts with the mission breifieng. After an emergency take-off, (which is followed by the destruction of the Kestrel) the player starts heading to Sudentor with his squad.
While the player is heading to Sudentor, President Vincent Harling gives a speech with Prime Minister Nikanor, a speech which he uses to end the war and promote peace. He succeeds with most forces, but a few warmongers still remain.
As you arrive in Sudentor, your squad starts singing The Journey Home song. Suddenly, a Yuktobanian squad appears. Rather than attack you, the squad of fighter joins you instead. Another squad soon follows the same lines. Soon a huge group of fighters have joined you, all singing The Journey Home.
Finally, your squad arrives at Sudentor. In an in-flight breifing, Pops tells you that you must assist the ground forces by attacking the warmongers fortificated in Sudentor. After defeating them, the infantry team manages to get past and take over the facility, opening the tunnel. In another in-flight breifing it is shown that the player must fly inside the tunnel and take out the core.
Once the player enters, it is revealed that Jack Bartlett will be flying head-on to the player in order to destroy the second core. Hamilton is also seen pursuing the player. Once the player reaches and destroys the core, he or she flies in a branch of the tunnel, awaiting Captain Bartlett. Once Bartlett arrives, the player must fly sideways in the tunnel in order to avoid crashing into Bartlett. If the player survives this far, he or she must then exit the tunnel ASAP, with enemy fighters flying headfirst into you. If not done quick enough, the player will smash into the closing hatches. If not though, the ending cutscene is seen with the team flying out of the tunnel in the last second. When Nagase asks where Hamilton is, Grimn answers with "He's dead, hit by a ricocheting plane".