ODST
The 22nd was at the battle of Installation 04 . They were under the command of Major Antonio Silva and First Lieutenant Melissa McKay. The 22nd left the Pillar Of Autumn in drop pods as the rest of the crew left in life boats. The 22nd set up base in a Forerunner structure where they were attacked by Covenant and Flood. The 22nd captured Private Wallace Jenkins infected but alive when the flood atacked the 22nd from underground. The 22nd learned that the flood was underneath after interigating Private Wallace Jenkins. The 22nd later captured the Truth And Reconciliation with Flood still onboard. While Major Antonio Silva wanted to return to Earth with Flood onboard, Lieutenant Melissa McKay knew that it would risk bringing the infection to Earth. She detonated a Fragmentation Grenade on the bridge, disableing the Truth And Reconciliation causing it to crash on the surface of Installation 04.
Sources Halo: the Flood