The Unification War was a war fought between the Union of Allied Planets and the Independent Planets from 2506 to 2511. The Central Planets had taken much of the system resources and technology and left the outer planets to fend for themselves. After years of unsatisfactory talks, the outer planets seceded from the Alliance and gathered support of other planets. Their aim was to start their own alliance, without the interference of the center planets. The Alliance could not accept this loss of face and so the war began.
Set 500 years in the future, humans have colonized and terraformed a planetary system of unknown location. The system contains Core planets and Border planets. As a general rule, the farther out one travels, the less civilized society becomes. The Core planets allied under a single government, The Alliance, and declared war upon those planets that wished to maintain their independence (The Independent Planets, often referred to as "Browncoats"). This series of events is recalled as the Unification War. The Alliance was victorious, and those surviving independents migrated towards the outer planets.
The Dust Devils were created to avenge the loss of the war and targeted Alliance officials.
Relatively little is known of the actual war itself (for example, it is unknown who actually started the war, though comments made by Jayne imply that it was the Alliance). One of the bloodiest battles of the war was the Battle of Sturges, which was fought over a hoard of money - it also took place entirely in space. Other notable conflicts are the Battle of Du-Khang in 2510 and a long winter campaign in New Kashmir. One of the last and most grisly major battles in the war was the Battle of Serenity Valley, in which Malcolm Reynolds and Zoë Alleyne fought (see below).
Battle of Sturges
Battle of Du-Khang
Battle of Serenity Valley
The Battle of Serenity Valley was a battle seen as the "last stand" for the hard-pressed Independent forces. It took place in Serenity Valley on Hera. The war ended there as the Independents were ordered to surrender by High Command.
Serenity crew involvement
Throughout the run of the series Firefly, it is revealed what most of the crew members of the ship Serenity did during the Unification War:
- Malcolm Reynolds and Zoë Alleyne Washburne served as Independent Faction soldiers in the 57th Overlanders brigade.
- During the commentary for "War Stories", Alan Tudyk speculated that Hoban Washburne was a pilot, although whether he was Alliance, Independent, or freelance is unknown. He also said he thought Wash was captured early on in the war and spent most of it as a POW (though most consider this to be humorous speculation on the part of Tudyk).
- Jayne Cobb did not serve in the war, although what he did do during the war has yet to be shown. He stated that the money was not good enough to justify the risk.
- Exactly what Simon and River Tam were doing during the Unification War is unclear, though they apparently didn't participate. They were born into a wealthy family on Osiris, one of the central planets, and supported the Alliance's goal of unification (though they may have simply been young and influenced by pro-Alliance propaganda). River was only around 10 years old at the time the war ended, seven years before the TV series takes place, and thus could not have taken any meaningful action during it. Simon apparently entered medical school around the time the war began (or slightly later), and may have gotten a student deferment (possibly influenced by his wealthy parents). The Alliance certainly had numerical superiority, and didn't need to scrape the bottom of the barrel for manpower. Given that the war lasted five years, Simon may have graduated before the war ended, but he said that after his internship he immediately began working as a trauma surgeon in one of the major hospitals of Osiris's capital city.
- The TV series never mentioned what Kaywinnet Lee Frye or Inara Serra did during the war. However, Inara told Mal in "Out of Gas" that she supported Unification.
- Derrial Book's past is mysterious even to the other crew members, though he may have past Alliance ties. In "Serenity: The Shepherd's Tale", it is shown he worked for the Independent Planets faction to sabotage a major Union of Allied Planets operation.
- New Firefly comic will tell the story of the Unification War. Entertainment Weekly, July 2, 2018