The duty of a sentinel is to stand guard and keep watch. Much like how shepherds meticulously tend to their flock of sheep to protect them against the elements, terrain and predators that could cause them harm.

Similarly, 108 Airmen with the 821st Contingency Response Squadron were constantly on guard during Exercise Hades Sentinel as they faced an opposing force, also known as OPFOR, whose sole purpose was to find and attack vulnerabilities within the squadron.

From April 26 to May 4 at Fort Hunter-Liggett in Jolon, California, the squadron formed a contingency response element that was expected to operate unabated in an austere environment with semi-prepared runway operations (SPRO) as part of its deployment readiness training.

“The exercise’s primary learning objective was to focus on 821st Contingency Response Element (CRE) and their ability to perform base defense,” Lt. Col. Aaron Sands, 821st Contingency Response Squadron director of operations said. “To assess our base defense capabilities, we invited the 721st CRS and 921st CRS to serve as OPFOR and to conduct a wide range of tactics against the CRE to include simulating uncooperative civilians, conducting covert sabotage, theft of equipment, simulated small unmanned aerial system harassment and overt complex attacks.”

When any contingency response squadron deploys, it forms a unit designated as a CRE, which encompasses multiple Air Force Specialty Codes, more commonly known as career fields, and CREs usually consist of more than 100 military service members and 30 different career fields.

The 821st CRS is designated to be deployment ready this fall, which is why there were numerous small-arms engagements with OPFOR, cargo airdrops into designated drop landing zones and other specialized areas of interest that prepare a contingency response squadron for an upcoming deployment alert cycle.

“Exercise Hades Sentinel also provided critical training for the CRE on how to conduct a complex mission with near simultaneous drop zone and landing zone operations while maintaining a heightened defensive posture,” Sands said.

In this training exercise, OPFOR had 24 team members, which was enough to test their CRE’s preparedness.

Furthermore, a C-17A Globemaster III airdropped cargo from its back cargo door and 821st CRS Airmen provided a capable drop zone, securing and protecting the area from OPFOR.

“Hades Sentinel was the first time that the 821st CRS was able to team up with the 62nd Operations Group from Joint Base Lewis-McChord who dedicated their C-17s and all their local training lines for the week of the exercise,” Lt. Col. Adam McDade, 821st Contingency Response Squadron commander said.

Fort Hunter-Liggett is a U.S. Army base which served as the battleground for Hades Sentinel. It provided unique elevated terrains and SPRO to simulate what the 821st CRS could expect in a real-world degraded deployment scenario.

“We also got some experience with hoist operations from an UH-60L Blackhawk helicopter to help the team get familiar with casualty evacuation operations,” Sands said.

Hades Sentinel was additionally a joint exercise with the U.S. Army’s C-Company 2nd Battalion and Colorado and California’s Army National Guard Unit, the 135th Aviation Regiment, which provided a UH-60L Blackhawk helicopter to perform casualty evacuation operations.

“I think the CRE performed well given the amount of OPFOR engagements they had to overcome,” Tech. Sgt. Matthew French, 721st Contingency Response Squadron non-commissioned officer in-charge of security forces intel and member of the opposition force said. “The hardest part of being in the CR is rapidly adapting to changing environments and I feel the CRE did great at repositioning forces, closing gaps in security and ensuring accountability of members after attacks.”

The OPFOR attacks happened randomly and often. Whether at 3 a.m. or enroute to a new location, OPFOR tested the combat readiness of the CRE.

“I enjoy getting to be the ‘bad guy’ because I learn better by seeing how the CRE reacts to our attacks, and it gave me a new perspective on how brainstorm better ways to overcome threats,” French said. “I think it allows all of us to see where we need to improve in relation to tactics, communication and accountability of our personnel.”

Multiple different weapon systems were used during this training exercise from M249/M240B light machine guns to an M2A1 Browning machine gun. Additionally, there was an M110 squad designated marksman rifle, an M203 grenade launcher and explosive white phosphorus grenades.

“I was most impressed with our night operational capabilities and proper employment of weapons systems to defeat an everchanging threat,” French said. “The best part was getting to test our own preparedness as CR members in a degraded environment.”

Since safety is the most important factor of any training exercise, simulation rounds were used in the M4 carbine rifles during the small arms engagements, and blank ammunition was used for all other training events and weapon systems.

“This was an overwhelming success in large part to the fantastic support from the opposing forces that consistently challenged the CRE,” Sands said. “Our ability to conduct drop zone operations opens a new avenue for training opportunities for both the CR and the participating flying units and we intend to maintain this mutually beneficial training going forward.”

Hades Sentinel served as an important refresher before the 821st CRS’s final certification event, Exercise Storm Crow, later this month. Despite the hot temperatures and rigorous tempo, one thing remains certain that the 821st CRS is well on its way to being ready for its upcoming alert deployment cycle later this year.