An Alliance gunship was a spacecraft slightly larger than the size of a standard shuttle. These vessels were operated from Tohoku-class cruisers, and seemed to be mainly used for escort. The term in common usage was often applied to both the Alliance Short Range Enforcement Vessel and Alliance Patrol and Enforcement Cutter spacecraft, both of them characterized by being small, short-range vessels with small crews and heavy firepower.
The captain of the I.A.V. Dortmunder ordered his ensign to deploy their gunships to engage Serenity and escort her back to the cruiser to be boarded when they found the vessel was conducting illegal salvage. However, when the officers were tricked by a "Cry baby", the gunship deployment was canceled.
Later, Serenity was captured by the Tohoku-class cruiser of Commander Harken. At least two gunships (each with two, flat, fixed wings) escorted Serenity to be boarded. As the Firefly-class transport ship docked, they were surrounded by dozens of more gunships (these with a more complicated wing configuration). 
Behind the scenesEdit
At least four different types of "fighter jet" style vessels appear in the Alliance arsenal. The first are the I.A.V. Dortmunder's (during "Serenity"). The second and third were seen with Harken's cruiser. These three are called "gunships". Later, the Alliance Short Range Enforcement Vessel (ASREV) appeared: three in "Trash" and one more in "The Message". The ASREV structurally is very similar—or possibly identical to—the gunships seen under the Dortmunder, although the ASREVs are more detailed. The production crew stated in Still Flying that the ASREV's first appearance was "Trash", which seems to indicate that gunships (even the similar ones aboard Dortmunder in the pilot episode) and ASREVs are completely different kinds of vessels.