The HECU is employed in the first Half-Life franchise game, to "clean up the mess" made in the incident of the Black Mesa Research Facility. They are deployed to eliminate extraterrestrial life, civilian personnel (to ensure that the incident is totally covered up so that the incident can be manipulated) and to regain control of the facility. The journal entries of Adrian Shephard found in Half-Life: Opposing Force’s instruction manual imply that the HECU was preparing for the Black Mesa Incident well in advance of the Resonance Cascade.