From Halopedia, the Halo wiki
During an engagement with UNSC forces, Sacred Promise was severely damaged, forcing its weapons to be taken offline. An attempt was made to elicit support from Devotion and fighter cover from Commitment and Patience. However, before any help could arrive, Commitment and Patience was crippled by a well aimed Magnetic Accelerator Cannon round which ruptured several fuel cells and put the main drive into a "runaway state."
The bridge crew of Commitment and Patience completely lost drive control and the ship crashed into the thin atmosphere of a local satellite after a failed attempt to stop the engines by forcibly ejecting the ship's fuel cells. The transmissions between Sacred Promise and other ships ended after the destruction of Commitment and Patience.
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