Halo 4: Terminal Locations Guide | Mission 2 'Requiem Terminal'
There are 7 Terminals hidden throughout Halo 4's campaign. The first Terminal, titled "War", is located in the final part of Mission 2 "Requiem" (Rally Point: Bravo).
How to find the "War" Terminal on Mission 2: Requiem:
After defeating the two Hunters (the massive Covenant with shields) on the platform, head inside the building and down the long hallway. At the end you'll see a large ramp heading up to an elevator. Before going up the ramp, go directly below it where you'll see the first terminal. It looks like a large column with a glowing spot on the front.
Congrats, you unlocked Terminal 1: War!