Ace Combat Zero
During the Belkan War, Riedel was Gault Seven of the Gault Squadron of Belka, under the callsign Feniks. The Gault Squadron mysteriously disappears, and the Belkan Airforce listed all members, including Riedel, as KIA.
During this time, Riedel and the rest of the Gault Squadron help create the rouge military terrorist / new world order faction "A World With No Boundaries", made up of people from around the world. When the group attempts to launch V2 rockets to major cities around the planet and create their new world order, the Galm squadron is sent to stop them. In the ensuing battle, Galm 1
shoots down the Gault Squadron, including Riedel. However, while the remains of his plane was found, his body was not.
Ace Combat 6
Riedel manages to flee the Osean Continent to the Anean country of Estovakia
Estovakia was in the midst of a civil war at the time, and the technology Riedel brought from Belka helped turn the tides in the war, in the favor of the faction he had sided with.
Eventually, this faction wins the civil war and gains control of Estovakia. This new militaristic leadership turned its eyes on Emmeria
, the neighboring Anean country.
This lead to the Anean Continental War, which began when Estovakia took control of the Emmerian capital city of Gracemeria.
The success of the siege of Gracemeria was largely successful because of the flying fortress, the Aigaion, an aerial aircraft carrier and Heavy Command Cruiser. The Aigaion was designed in line with the technology Riedel had taken from Belka, and was largely based on Belka's Hresvelger aircraft. This placed Riedel and his information in a powrful place during the war. The Aigaion, and its sister ships the Kottos and Gyges, along with their deadly cruise missile system, formed the Estovakian Aerial Fleet, which proved instrumental in the occupation of Emmeria.
When Emmeria finally struck back and attacked the fleet, Riedel, leading a high ranking Strigon squadron, set out to defend his fleet. Taking off of the Aigaion, he does combat with Garuda 1
, who successfully shoots him down. Riedel's fleet of advanced ships are completely destroyed, which opens the way for Emmeria to retake Gracemeria. However, despite being once again shot down, Riedel's body is still missing. It is unknown what his actions are following the events of Ace Combat 6.
Riedel's callsign is Fenkis (Phoenix), which may be a reference to how he is continually seemly killed or goes missing, only to return as a major military figure. He appears as an enemy Ace in both Ace Combat Zero and Ace Combat 6, and in 6 his plane features the paint job of Galm 1, who shot him down in Ace Combat Zero.