Rex told him. He told it in the structure of a report, starting with his ambush to try stopping the Legion, but he didn't tell Alexander that he killed them all, then the extraction of Apollo and the others, and finally Rex's pursuit through the earthen passage, the recovery of the captives, and the recovery of the key.
He presented the information in a manner that was factually accurate regarding its individual components while strategically omitting certain details. He left out what he did in the canyon that caused the result and made it seem like the outcome was just due to the extraction ring not working and the Legion thinking their position was no longer good.
He delivered his report calmly and in an orderly fashion. Alexander listened with the professional attention of someone accustomed to receiving field reports. When Rex finished, Alexander looked at him for a long moment.
