Battle of Oban

The Battle of Oban was an engagement fought on the planet Oban in July 16, 2558. It was waged between the Prometheans and their religious followers and the United Nations Space Command.

Background
In a plot to acquire the other half of the Janus Key onboard the UNSC Infinity, Dr. Catherine Halsey and Jul 'Mdama devised to launch an offensive against the UNSC solely in order to draw the Infinity out into a vulnerable position.

The battle
After the planet was attacked by Jul 'Mdama's Covenant and their Promethean allies, 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 an M12 Chaingun Warthog and pursue the Phantoms, but they were ambushed and pursued by Promethean Crawlers. They dispatched several of the Crawlers and Palmer jumped off 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.

A new, much more durable type of Promethean Knight was encountered on Oban during the attack.

Aftermath
Jul's forces suffered heavy losses, while inflicting only minor damage to a new power station and briefly pausing the planet's colonization efforts. Captain Lasky chided Commander Palmer for acting hastily despite there being no proof Jul 'Mdama was ever present on the planet. The following day, when the Infinity jumped into slipspace, its slipspace drive experienced an anomaly which trapped them in an uncharted system. Unbeknownst to them, Dr. Halsey and 'Mdama possessed an artifact capable of contacting the Infinity's Forerunner components, including her slipspace drive, allowing them to confine the flagship within the system.

List of appearances

 * Halo: Escalation
 * Halo 5: Guardians