After the planet Oban was attacked by the Covenant and their Promethean allies on July 16, 2558 a joint Spartan-UNSC Marine Corps operation was deployed in response to the attack. During the battle, Spartan Thorne was ambushed by a Promethean Knight but he was saved by Commander Palmer. With the Prometheans' presence, Palmer ordered all UNSC forces to search and find Jul 'Mdama. Meanwhile, Spartan Joel Thomas ordered an airstrike on two Type-44 Phantoms near Palmer's position. Palmer ordered Thorne to get to a M12 Warthog LRV and pursue the Phantoms, but they were ambushed and pursued by Promethean Crawlers. They dispatched several of the Crawlers and Palmer jumped out of a cliff, directly above the Phantoms. The Warthog landed on the ground, injuring Thorne, and the Phantoms prepared to shoot their heavy plasma cannons at them. However, a GA-TL1 Longsword appeared, destroying both Phantoms, and saving Palmer's and Thorne's lives.