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Osea, officially known as the Osean Federation, is a large nation and international superpower located on the Osean continent. Osea encompasses a majority of the continent's western landmass, and is bordered by Wellow to the north; Belka, Ustio, and Sapin to the east; and an unknown country to the south. Its capital, Oured, is located on the tip of Osea's southeastern peninsula near Oured Bay.

Osea is a highly developed nation that possesses a large population, extensive infrastructure, thriving economy, and well-outfitted military force. Osea is also considered one of the world's foremost leaders in aeronautics and space-exploration development.

Osea is the player character's homeland in Ace Combat 5 and an allied country in Ace Combat Zero; it will also make an appearance in Ace Combat 7: Skies Unknown.


Pre-20th century


A view of the Osean capital, Oured

The country of Osea is known to have existed prior to the 19th century. According to navigational charts from the early modern era, several Osean cities, such as Oured and Bana City, have existed for quite some time.[1] The nation's history is marked by territorial expansion and imperialism, which resulted in tensions with the neighboring Belkan Empire throughout the 19th and 20th centuries, and the nations of Usea during the late 1990s.[2]

Osean War (1905–1910)

Between 1905 and 1910, Osea was embattled with Belka in what became known as the Osean War. During the five-year conflict, Osea was attacked by the newly-formed Belkan Air Force, which inspired the later creation of the Osean Air Defense Force.[3]

Cold War (circa 1950–1995)

Over the course of the mid-20th century, Osea flourished and began to expand its political influence around the globe. By the 1980s, Osea was in the midst of a cold war with the Union of Yuktobanian Republics, its rival superpower across the Ceres Ocean. The threat of unrestrained nuclear war between the two nations was a frighteningly real possibility. The era's ongoing arms race compelled the Osean Department of Defense to develop atmospheric weapon systems under the Strategic Defense Initiative (SDI) to counter recent advancements in Yuktobanian ballistic-missile technology. It was during this time that the Arkbird maneuverable spacecraft was first conceived.[4]

In the late 1980s, Osea—believing that valuable resources existed beneath the newly created state of Ustio—secretly backed separatist movements within Belka prior to the 1988 federal law review, which was motivated by Belka's ongoing recession.[citation needed] As the Belkan government sought to alleviate its nation's economic troubles, Osea formed a joint corporation with Belka to oversee Osea's acquisition of the Great Lakes region in September 1991; the Five Great Lakes Resource Exploration Company quickly collapsed after a corruption scandal revealed that Osea had deliberately underfunded the venture and falsified financial reports in an effort to further destabilize Belka's economy.[5][6]

As the decade came to a close, however, Osea purchased a large portion of Belka's lands to the northwest and southeast of the Great Lakes. Several Belkan cities, such as Wesson and Rutherford, subsequently became Osean.[7] Despite this, a great deal of resentment and animosity still existed between Osea and Belka.

Belkan War (1995)


In March 1995, Belka declared war on the Osean Federation and invaded much of the territory Osea had acquired several years earlier. Osea consequently allied itself with Ustio, Sapin, and Yuktobania to form the Allied Forces and repelled the Belkan Army through the initiation of Offensive Campaign No. 4101. During the conflict, Osea contributed a majority of the military forces sent to contain the Belkans' offensive, including the OMDF's 3rd Fleet,[8] the Osean Army's 101st and 122nd Airborne Divisions,[9] and numerous OADF fighter squadrons. In addition, Osea began constructing the Strategic Orbital Linear Gun (SOLG) as a countermeasure against Belka's technologically advanced military.

In late May, Osea and the other Allies withdrew from the treaty of non-aggression at the Assembly of Nations. The announcement came with a simultaneous large-scale air assault on Area B7R, which led to the end of Belka's air superiority in the region. On June 6, as the Allies prepared to invade Nord Belka, Belka detonated seven nuclear warheads along the Waldreich Mountains, killing 12,000 people and causing the cessation of hostilities on both sides.[10][11]

Era of peace (1996–2010)

"The world was once again at peace. And, thanks to them, it seemed it would last forever."
Albert Genette[12]

In the aftermath of the war, Osea acquired a large portion of South Belka and renamed it "North Osea". Once again, historically Belkan cities, such as Lumen and Sudentor, were assimilated by Osea. The South Belka Munitions Factory, an arms manufacturer based in Sudentor, was renamed North Osea Gründer Industries and began outfitting the Osean Defense Forces with advanced military hardware.[13]

In 1996, Osea signed a bilateral agreement with Yuktobania that officially ended the Cold War.[14] The treaty signing compelled the survivors of the OADF's Wizard Squadron to plot the Osean president's assassination, but were either killed or arrested by Osean Special Ops.[15]

Mass Driver Docking

Osea's Arkbird was a technological milestone in manned spaceflight

Following the peace pact, Osea and Yuktobania began to focus money and resources towards collaborative projects, such as the reborn Arkbird project[16] and the humanitarian relief efforts following Ulysses's planetfall in 1999. Osea remained relatively unharmed by Ulysses, and the population of its capital, Oured, swelled with the influx of refugees from foreign nations.[17] Scientists and specialists from the two superpowers later collaborated to address the Ulysses fragments that still lingered in orbit; it was ultimately decided that the Arkbird would be employed to clear the orbiting debris. In the early 2000s, Osea and Yuktobania spearheaded a plan to create an international space station in conjunction with Verusa and the Federation of Central Usea.[16]

Usean Continental War (1998)

In 1998, Osea extended an offer of military allegiance to the nations of Usea. Despite objections from Usea's northern and western states, the southern states allied themselves with Osea, sparking the Usean Continental War.[2] The treaty is assumed to have been dissolved following the war's conclusion.

Post-Ulysses period (2000s)

In 2004, Vincent Harling was elected as the 48th President of the Osean Federation. Throughout his first term, Harling's peace policies strengthened Osea's ties to Yuktobania and led to the creation of Basset Space Center. In 2008, Harling was reelected to a second term on Bright Hill, and Osea hosted the annual G7 Summit aboard the Arkbird. The meeting saw an historic push to ratify several anti-proliferation treaties, including a Strategic Arms Reduction Treaty and a Comprehensive Nuclear Test Ban Treaty.[18]

Circum-Pacific War (2010)

In late September 2010, Osea experienced a series of airspace intrusions by Yuktobanian Air Force aircraft shortly before its former ally declared war on the Federation on September 27, 2010.[19] Over the coming days, Osea fended off several Yuktobanian airstrikes and suffered considerable losses at Eaglin Straits. On October 22, President Harling departed the capital and disappeared for several months. In his absence, his second-in-command, the patriotic Vice President Appelrouth, usurped control of the Osean government[20] and sanctioned a full-scale ground invasion of Yuktobania.[21]

The Osean Army's invasion of Yuktobania advanced quickly due to the efforts of Wardog Squadron. However, on November 4, Osea suffered two deadly terrorist attacks perpetrated by Yuktobanian special forces; at least 300 Osean civilians were killed in the attacks.[22] Later that month, the Vice President's peace ceremony in November City was attacked by Yuktobanian aircraft; however, there were no reported civilian casualties.[23]

Shortly after the fall of Cruik Fortress on December 6, Wardog was exposed as traitors and summarily executed while attempting to escape over the northern Ceres Ocean.[24] Following these events, the Osean Army was unable to capture the Yuktobanian capital of Cinigrad and became stalemated with the Yuktobanian forces.

In late December, President Harling returned to the capital and regained control of his office from Appelrouth.[25] On December 30, Harling hosted a televised press conference with Yuktobanian Prime Minister Nikanor and revealed that the war had been orchestrated by an unspecified group, which planned to use a weapon of mass destruction against the two nations.[26] With the war officially over, a coalition force of Osean and Yuktobanian fighters and ground troops attacked Sudentor, North Osea to halt the Belkans' plans to commit mass murder. The Belkans were ultimately defeated by Razgriz Squadron, and Osea was spared.[27][28]

For several years after the war, the circumstances behind the "Belkan Conflict" were kept secret by the Osean government. Four years later, Harling announced at the 2014 Osean Federation Council meeting that all information pertaining to the war would be released to the public in 2020. It is presumed that Osea, under Harling's leadership, worked to reestablish the alliance Osea and Yuktobania had shared prior to the war.[29]

Osea-Erusea Conflict

At some point after the conflict, the Osean Federation became engaged in combat with the reformed Kingdom of Erusea for, as of yet, unknown reasons.[30]


Political structure

One of the largest nations of the Osean continent, the Osean Federation is a democratic federal state divided into six administrative regions: Burton, Glennon, Stockham, Lindsey, Rinehart, and Eversole, the last of which serves as the capital district.[31] The Osean populous is represented in a legislative body known as the Osean Federation Council. The national government is headed by a popularly elected president who assumes the executive office for a four-year term; it is unknown if the Osean presidential office carries a term limit.

The Osean government includes roles such as Vice President[23] and Foreign Minister[5]; governmental departments include the Ministry of Defense[4] and the Osean Aeronautics and Space Administration.[32]

Armed forces

Osea supports one of the largest and most well-equipped military forces in the world. Known as the Osean Defense Forces, the nation's military is comprised of the Osean Air Defense Force, the Osean Maritime Defense Force (which supports a marine division), the Osean Army, and Osean Coastal Defense Force.



  1. Historical Map of Strangereal, ACES WEB. Published 2004. Retrieved August 29, 2016.
  2. 2.0 2.1 Ace Combat: Assault Horizon Legacy.
  3. Belkan Air Power (Second Edition), Ace Combat Zero (JP). Published July 18, 2005. Retrieved February 8, 2014.
  4. 4.0 4.1 "Road To A Maneuverable Orbiting Spacecraft", GAZE: Arkbird Declaration Summit 2008. Retrieved January 11, 2017.
  5. 5.0 5.1 WORLD / WORLD NEWS / ПОСЛЕДУЙТЕ, Ace Combat 5 Website. Retrieved January 9, 2017.
  6. Ace Combat 5: The Unsung War Perfect Guide, page 248.
  7. Cutscene 10, Ace Combat Zero: The Belkan War.
  8. Juggernaut, Ace Combat Zero: The Belkan War.
  9. Flicker of Hope, Ace Combat Zero: The Belkan War.
  10. The Stage of Apocalypse, Ace Combat Zero: The Belkan War.
  11. Cutscene 09, Ace Combat Zero: The Belkan War.
  12. Cutscene 01, Ace Combat 5: The Unsung War.
  13. Aces At War: A History, page needed.
  14. Aces At War: A History, page needed.
  15. Assault Records #156: Iosif Beletsky, Ace Combat Zero: The Belkan War.
  16. 16.0 16.1 "Ark After Stonehenge", GAZE: Arkbird Declaration Summit 2008. Retrieved January 11, 2017.
  17. "The World in Unison with Emmeria", GAZE: Last Christmas. Retrieved January 11, 2017.
  18. "Arkbird Declaration", GAZE: Arkbird Declaration Summit 2008. Retrieved January 11, 2017.
  19. Open War, Ace Combat 5: The Unsung War.
  20. Handful of Hope, Ace Combat 5: The Unsung War.
  21. Lit Fuse, Ace Combat 5: The Unsung War.
  22. Reprisal, Ace Combat 5: The Unsung War.
  23. 23.0 23.1 Journey Home, Ace Combat 5: The Unsung War.
  24. Final Option, Ace Combat 5: The Unsung War.
  25. Cutscene 22, Ace Combat 5: The Unsung War.
  26. Cutscene 26, Ace Combat 5: The Unsung War.
  27. ACES, Ace Combat 5: The Unsung War.
  28. The Unsung War, Ace Combat 5: The Unsung War.
  29. Cutscene 29, Ace Combat 5: The Unsung War.
  30. Ace Combat 7: Skies Unknown.
  31. GAME Watch Impress - 「エースコンバット5 ジ・アンサング・ウォー」: "An increasingly greater view of the world". Retrieved August 29, 2016.
  32. "Accelerating the Peace Process", GAZE: Arkbird Declaration Summit 2008. Retrieved January 11, 2017.
  33. Cutscene prior to Chain Reaction / Reprisal, Ace Combat 5: The Unsung War.

Start a Discussion Discussions about Osea

  • Osea and it's contributions to Strangereal

    20 messages
    • That's a very incorrect statement. Yuktobania started a war with Osea, but Osea utilized its air power as well as its Arkbird and halted ...
    • Very true, very true. It's not that he didn't care about defending, it's that he believed that peace could be achieved.
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