From Halopedia, the Halo wiki
On August 12, 2552, Mallarde commanded the Grafton during the Battle at Szurdok Ridge. While providing fire support for UNSC ground forces during the battle, the ship was soon ordered to destroy a Covenant teleportation spire. After Noble Six disabled the spire's shield, Mallarde ordered the ship to use it's Magnetic Accelerator Cannon on the spire, destroying it. The victory was short-lived as the Covenant CSO-class supercarrier Long Night of Solace destroyed the Grafton with its ventral energy projector, killing Mallarde and the rest of the crew.