Longhorn Valley was a geographical location in the Military Wilderness Training Preserve within the Highland Mountains of the planet Reach. It was a sloped region ten kilometers across that contained a thick forest of Douglas firs and trampled fields. The Big Horn River ran through the middle of the valley.
During their training, the SPARTAN-IIs became familiar with the valley during their many training exercises in the area.
On July 23rd, 2552, the night of the initial Covenant incursion, the UNSC Army fireteam 3 Charlie was on patrol in the valley. They were then sent to investigate a disturbance at the Visegrad Relay.
During the Fall of Reach on August 30th, the valley was occupied by the Covenant, who built large defensive encampments in preparation for excavating the Forerunner complex beneath Menachite Mountain. The valley was scorched when a team of SPARTANs used a Fury Tactical Nuclear Weapon to destroy a Covenant cruiser that was holding position overhead. The valley was presumably glassed.
List of appearances
- Halo: The Fall of Reach (First appearance)
- Halo: First Strike
- Halo: Reach
- Halo: Fall of Reach
- Halo: The Fall of Reach - The Animated Series