The ODST pair, Bravo-21 and Bravo-22, were tasked with calculating the crash site of John-117 who was on his way to Earth, having jumped out of the Forerunner Dreadnought. Meanwhile, a MarineBattalion was assigned the objective of holding off the Covenant forces in the area until the Spartan's re-entry. After retrieving a laser designator, a Pelican dropship dropped off a Warthog for the two ODSTs, who drove it along a highway to the rest of the Marines' position in Sector Six. Bravo-22 was injured during the ride by a Spiker round, but he was able to carry out the mission.
Upon arriving at the Marines' position, the ODSTs joined them in holding the Covenant off until John-117's re-entry. A Phantom arrived, dropping off Covenant reinforcements, including a Jiralhanae Chieftain who killed Bravo 21 after he had neutralized two other Jiralhanae. Meanwhile, the rest of the Marines were being overrun by the Covenant forces, including air support by Banshees. Bravo 22's wounds were treated by CorpsmanR. Coney, while the rest of the Marines started to fall back. A Marine named Scottlee was pinned to a wall by Spiker rounds. As Coney was cutting him loose, Bravo 22 opened the laser designator and successfully tracked Spartan-117's re-entry vector. After succeeding in their mission, the UNSC survivors fell back into a bunker, killing the Jiralhanae Chieftain with a rocket launcher just as the bunker's doors closed.
Numerous Marines were killed in the fighting, and Bravo 22 was injured along with many of the other Marine survivors. The battle is referred as "a mission that may secure the salvation of the entire galaxy", and it indeed was: Bravo-22 was able to track Master Chief's landing point with the laser designator, allowing the UNSC forces to quickly locate the Spartan and use him for stopping the Prophet of Truth's plans.
In Halo 3, Master Chief is seen falling out of the sky during nighttime, but in the video of this battle, the Marines track him plummeting towards Earth during the day, which means that the crash zone and the battle are in different time zones. Indeed, John-117 ends up falling near Mount Kilimanjaro in Africa, far from the location of Sector Six.