Halo First Strike 2

"Red-One," Joshua's voice called over the SQUADCOM. "I'm a half-klick ahead of you. You need to see this."

"Roger," Fred told him. "Red Team, hold here and wait for my signal." Acknowledgment lights winked on. In a half crouch, Fred made his way toward Joshua. There was light ahead: The shade thinned and vanished because the forest was gone. The trees had been leveled, every one blasted to splinters or burned to charred nubs.

There were bodies, too; thousands of Covenant Grunts, hundreds of Jackals and Elites littered the open field. There were also humans-all dead. Fred could see several fallen Marines still smoldering from plasma fire. There were overturned Scorpion tanks, Warthogs with burning tires, and a Banshee flier. The flier had snagged one canard on a loop of barbed wire, and it propelled itself, riderless, in an endless orbit.-Chpt.2 pg.28

Lieutenant Buckman, the Marines' CO, had been ordered to send the bulk of his men into the forest in an attempt to flank the enemy. He had called in air support, too. He got it.

Reach HighCom must have realized the generators were in danger of being overrun, so someone panicked and sent in bombers to hit the forest in a half-klick radius. That wiped out the Covenant assault wave. It also killed the Lieutenant and his men. What a waste.-Chpt.2 pg.32