In mid-December 1991, Sapin acquired a portion of Belka's southernmost territories east of the Great Lakes, which extended the kingdom further north. The recently seceded Republic of Ustio became Sapin's new neighbor to the north.
Belkan War (1995)
Main article: Belkan War
On March 25, 1995, Sapin's northwestern territories were invaded and occupied by the Belkan Army. Although Sapin's military was caught off guard and outmatched by Belka's superior military power, the Belkans were unable to capture Sapin's capital, Gran Rugido. The kingdom ultimately allied itself with Osea, Ustio, and Yuktobania to form the Allied Forces and repulse the Belkan onslaught.
By May 13, Sapin and the Allied Forces had expelled the Belkans from their lands and began an offensive into Belka's territory. Following the tragic events of June 6, Sapin's forces agreed to an immediate ceasefire. On June 20, delegates from Sapin were present at the signing of the Lumen peace accords, which officially ended the war.
During the treaty signing, the Sapin Air Force's Espada Team and Escudo Squadron patrolled the airspace above the ceremony. Two additional squadrons (Lanza and Armadura) were scheduled to relieve Espada and Escudo, but were destroyed while attempting to take off from a sabotaged runway, leaving Espada and Escudo to guard the peace ceremony and remain on stand-by alert should anything happen near Gran Rugido.
In the months following the war's conclusion, various military officers and personnel from Sapin, Osea, Yuktobania, and Belka formed the rebel organization A World With No Boundaries. One such example was Espada Team, which defected from the Sapin Air Force and joined the coup forces sometime prior to December 25. When the terrorist group later bombed Lumen and Valais Air Base, the Sapinish pilots were present to fly escort for the experimental XB-0 Hresvelgr gunship.
The Kingdom of Sapin is a monarchy ruled by either a king or queen who inherits the Sapinish throne through the right of primogeniture. Addition details regarding the kingdom's political structure remain unknown. However, Sapin is known to have been a neutral country prior to the Belkan War's outbreak in 1995. Sapin in presumed to have maintained amiable relations with its former allies, Osea and Ustio, in the years after the war.
Sapin's location to the northeast of Oured Bay provides it with a Mediterranean climate and access to maritime shipping routes into the Spring Sea. Sapin also maintains joint control over the Futuro Canal, which is located along Sapin's northwest border, with Osea. Information regarding the nation's topography is scarce; however, it is known that the landscape becomes more mountainous in the north towards the Belka-Ustio border.
- The Kingdom of Sapin is regarded as an allegory of Spain, which is itself a constitutional monarchy:
- Sapin's name is an anagram of "Spain";
- The people of Sapin possess Hispanic surnames and speak with Hispanic accents;
- Sapinish cities such as the capital, Gran Rugido ("Great Roar"), and military designations such as Espada ("blade, sword") use Spanish nominatives; and
- The national flag of Sapin bears a coat of arms similar to the Spanish flag.
- The SP color schemes of the Rafale M and J35J Draken in Ace Combat Zero feature the colors of the Spanish flag.
- Project Aces's conceptualized game, Brave Arms, was intended to be set in the Kingdom of Sapin, but was not a flight simulator and was ultimately cancelled.