Unification Day is a holiday celebrated in the fictional universe of the science-fiction television series Firefly

Firefly (TV series)

Firefly is an American space western television series created by writer and director Joss Whedon, under his Mutant Enemy Productions label. Whedon served as executive producer, along with Tim Minear....

. It marks the day in which the Alliance

Alliance (Firefly)

The Alliance is a fictional supra-governmental entity in the Serenity franchise, a powerful authoritarian government and law-enforcement organization that controls the majority of territory within the known universe...

 forces defeated the resistance ("Browncoats") in the Unification War.

"The Train Job

The Train Job

"The Train Job" is the second episode of the American science-fiction western television series Firefly created by Joss Whedon, although it was the first to be shown...

", the second episode of the series (although Fox

Fox Broadcasting Company

Fox Broadcasting Company, commonly referred to as Fox Network or simply Fox , is an American commercial broadcasting television network owned by Fox Entertainment Group, part of Rupert Murdoch's News Corporation. Launched on October 9, 1986, Fox was the highest-rated broadcast network in the...

 originally aired it before the pilot episode "Serenity

Serenity (Firefly episode)

"Serenity" is the two-hour series pilot for the American science fiction television series Firefly created by Joss Whedon. However, Fox executives were not satisfied with this as a pilot, and so instead, "The Train Job" was created as a second pilot and was the first episode of the series aired....

"), opens with Mal

Malcolm Reynolds

Malcolm "Mal" Reynolds is a fictional character and main protagonist in the Firefly franchise. Reynolds is played by actor Nathan Fillion in the 2002 TV series Firefly and the 2005 film Serenity. In the series, Reynolds is the captain of the Firefly-class spaceship Serenity...

, Zoe, and Jayne in a bar during a Unification Day celebration. Malcolm's brown coat and his disinterest in celebrating Unification Day lead to a brawl.