Ferinus Campaign

The Ferinus Campaign was an extremely large military conflict that took place on the planet Ferinus, which was largely over artifacts and other extensive Forerunner relics. Buried underneath the planet, the Jiralhanae were mining for the ancient relics when the zealot Stel 'Vadam arrived in orbit, doing battle with the Jiralhanae fleet in orbit. Stel 'Vadam narrowly escaped the battle to land on the ground, only for his to be shot down by surface-to-air batteries the Jiralhanae had planted on the ground.
When he managed to escape, the commander of the Sangheili managed to meet up with a navy officer named Leonardo Simmons, whom he saved from a Jiralhanae chieftain. The two made their way throughout the colony's wilderness before being picked up by several marines and taken to the forward base.