The auxiliary bridge in the engineering hull of a Galaxy-class starship, from which the stardrive section is commanded after the saucer has separated.
The battle bridge is on deck 8 of the Enterprise-D, at the top of the stardrive section. It is smaller and plainer than the main bridge, with stations arranged for combat, and is used only when the ship divides.
It is first seen in Encounter at Farpoint, when Picard takes the stardrive section back to face Q after sending the saucer on with the families. In The Arsenal of Freedom, Geordi La Forge commands from it against the automated weapon above Minos.
In The Best of Both Worlds, Part II, Commander Shelby takes the battle bridge while Riker remains in the saucer, the two halves attacking the Borg cube together so that Data and Worf can slip aboard and seize Locutus.