Stier Castle is an historic Belkan castle positioned on the southern edge of the border between Belka and North Osea (formerly South Belka) in the Waldreich Mountains, northwest of Sudentor. In modern times, Stier Castle witnessed several important events that shaped the outcomes of the Belkan War and Circum-Pacific War.
Stier Castle is situated on the northern banks of Lake Edelwasser and is surrounded by rolling hills and sparsely populated farmland. The castle is connected to a small rural town just north of the lake. Stier Castle stands on the southern point of an oblong promontory known as a drumlin, which provided protection against attacks from the lakeside. The keep is positioned atop two staggered tiers, and the castle's northern grounds are surrounded by tall defensive walls with watchtowers.
A short distance east of the castle, on the north bank of Lake Edelwasser, sits a small partially-covered port, during Operation Keynote in 2010 Gunboats were continuously deployed from this port to patrol the lake.
On June 6, 1995, Stier Castle witnessed one of the seven nuclear detonations only a few dozen miles to the southwest. Despite being close to ground zero of the detonation, Stier Castle miraculously survived the blast.
Several months later, on December 25, Stier Castle witnessed the destruction of the XB-0 Hresvelgr after the extremist group A World With No Boundaries used it to bomb Ustio's Valais Air Base. Galm Team shot down the heavy command cruiser northeast of the castle, which remained unscathed during the engagement.
On October 22, 2010, Osean President Vincent Harling was kidnapped by Belkan operatives and imprisoned in Stier Castle. The president would remain confined in Stier Castle until December 9, at 0500hrs, when Osean fighters and marines launched a rescue operation to free Harling.
An infiltration team entered the castle and freed the president, but became pinned down by intense enemy crossfire. The Osean fighters consequently punched a hole in the castle keep's west wall in order to allow the infiltration team to escape with the president. The operation was successful and, despite the aforementioned damage, Stier Castle remained standing.
- Stier Castle appears numerous times in-game:
- Due to the location changes in the briefing maps from Ace Combat 5: The Unsung War to Ace Combat Zero: The Belkan War, Stier Castle's location did not remain consistent. The briefing prior to "Ancient Walls" places the castle in northwestern Belka, while the briefing prior to "The Stage of Apocalypse" shows it as being southwest of Sudentor.
- "Stier" is German for bull.