Halo Flood 12

With their leader down, the Grunts broke ranks and
began to scamper away. The Master Chief cut their
retreat short in a hail of bullets. He eased up on the trigger, felt the silence settle in around him, and knew he had made a mistake. The veteran had damned near blindsided him. How? He realized with a start that he was still fighting like part of a unit. Though he was trained to act independently, he had spent most of his military career as part
of a team.

The Elite had managed to flank him because he was simply accustomed to one of his fellow Spartans watching out for him. He was cut off from the chain of command, alone, and most likely surrounded by the enemy. He nodded, his face grim behind the mirrored visor. This mission would require a major revision in his tactics.-Chpt.2 pgs.61-62