The soldiers killed by Ray Garrison were revived with the help of a large force.
Author Dave Wilson:
Eric Heisserer (script writer), Bob Layton (cartoon) | Ray Garrison, an elite soldier who was killed in the battle, is revived with advanced technology that gives him great human strength and fast healing abilities. In his newfound ability, he follows the man who killed his wife, or at least the man he thinks killed his wife. He must know immediately that everything he learned is untrustworthy. The real question: can he trust himself?