Operation B: Steadfast Pursuit
From Halopedia, the Halo wiki
Operation B: Steadfast Pursuit is the second operation of Halo: Spartan Strike. This operation is an in-universe simulation of the Battle of Installation 03, following a Spartan Headhunter's search for the Conduit.
As the Solemn Penance entered slipspace over New Mombasa, our team radioed Command to say they'd recovered the Conduit. Moments later, the slipspace rupture devastated the city... And our team was never heard from again.
We lost the Conduit, but their heroic sacrifice kept it out of Covenant hands.
Five years later, the UNSC picked up a faint signal coming from Gamma Halo... When we learned it was coming from the Conduit, we sent a Spartan to investigate. But hang on to your HUDs, 'cause we weren't the only ones tracking that signal!