The first conception of the Sentinels was proposed on July 14th, 1948 by SRPA Tactical Ops. SRPA sought to create a class of super-soldiers that were on par with the Chimera, and as well to find an immunity to the Chimeran virus which easily brought about Europe's downfall. To this end, SRPA authorised the creation of Project Abraham.
Project Abraham enlisted candidates from the military who were "resilient, capable soldiers with strong ties to country and honor." The participants were told that they had volunteered for research in seeking a cure to the "European influenza" and all information about the Chimera was withheld. The Project also offered a $10,000 incentive for anyone who wanted to enlist.
Project Abraham recruited the finest scientific minds from around the globe. The project's research was led by Dr. Fyodor Malikov, whose years of knowledge of the Chimeran virus and his past experiments with the Cloven was invaluable in the project's efforts.
The outcomes of the project were initially largely fatal as some of the subjects developed severe body mutations while others fell into comas. Nevertheless Project Abraham succeeded in its goals and it was shut down on December 15th, 1950. All survivors of the project were placed in SRPA to begin immediate Sentinel training.
The Sentinel Program
SRPA released many of the surviving Project Abraham candidates into their respective military branches while under clandestine observation until being reclaimed after being exposed to the Chimeran virus when sent into combat. On July 13th, 1951 SRPA Executive Director Lyle K. Parsons ordered the reclamation of all surviving Project Abraham test subjects to be analyzed in order to avoid the threat of further transformation, such as the case of Jordan Shepherd, who transformed into the Chimeran entity known as Daedalus.
Black Ops teams were sent to retrieve the subjects, who are then sedated as a precaution given the lack of knowledge of how far the virus had progressed within them. The soldiers were taken to the nearest SRPA base where they were physically examined for at least two days until being fully allowed to join the Sentinel Program.
The Sentinels are soldiers from previous military branches that have been enhanced with a specific strain of the Chimera virus developed by Project Abraham. Because of Project Abraham's experiments, they have been gifted with superhuman abilities that most Chimera display, such as abnormal strength, speed, stamina and limited regeneration. Most Sentinels seem to be on par with Hybrids in terms of physical attributes and have been shown to survive falls from great heights. They can essentially be described as being part human and part Chimera.
Due to their abilities and immunity to the Chimeran virus, the Sentinels are specifically tasked with the most dangerous missions, with each Sentinel said to be worth at least three U.S. Army Rangers each, and even in death they could possibly claim hundreds of Chimeran lives. Sentinels operate in small squads of four, with one leader per squad, much akin to a fireteam; however, sometimes the squads are teamed up to take on particularly daunting missions (as is mostly the case depicted in the book Resistance: The Gathering Storm).
Despite the Sentinels' immunization to the Chimeran virus, their condition is simply stalling their inevitable transformation into Chimera. Therefore, under SRPA Code 760-B, all Sentinels are required to be inoculated daily with clinical inhibitor treatments to keep the virus under control. Sentinels are also employed with I-Packs which administers an aerosol version of the inhibitor which the user inhales through the nose connected to the I-Pack, should a Sentinel in question is not near a licensed SRPA inhibitor clinic. As the I-Pack is only meant to be a temporary solution Sentinels are required to visit the nearest SRPA base for treatment on a regular basis.
Sentinels are also checked by their personal psychologists and physicians in order for them to make sure they are mentally stable, which is made more difficult because of the fact that every Sentinel was prone to injuries associated with inhibitor shots. The many mental instabilities among most Sentinels who struggled to cope beside combat related stress is the fact that they were cut off from their families and anyone close to them given the absolute government secrecy of the Sentinels.
Sentinels reserved the same military discipline as regular soldiers in the armed forces. As the case of Joseph Capelli for his belligerent personality and mild assault streak, he was given numerous suspensions, brief imprisonments, and a rank demotion. Also, given the classified nature of the Sentinels they are officially declared deceased, and Sentinels are given a Code of Zero Tolerance from ever directly contacting the public, and even from their own families. In the case of Benjamin Warner, he was given several citations for contacting his family and was lastly detained in the brig when leaving his post for almost personally meeting his family. Given the rising situation of the Chimeran War, many Sentinels had their sentenced reduced due to their abilities and needs in the battlefield.
As of 1957, it is unknown how many Sentinels have survived throughout the course of the Chimeran War; the only known Sentinel to be alive at the end of Resistance 2 and Resistance 3 was Joseph Capelli.
Sentinels can be awarded with accolades such as SRPA's Bronze Star, Silver Star and Gold Cross for their actions in operations, mainly going to soldiers who take initiative and show leadership in times of crisis.
During the early stages of the Sentinel Program, soldiers of whatever role whom showed excellent leadership were given officer training and placed in command of their own teams, such as Hank Leavitt who wasn't even a non-commissioned officer for Alpha Team during the Battle of Fort Anchorage but due to his actions he ended up as a lieutenant and the first commander of Echo Team.
- Battle of Fort Anchorage - Date unknown. (Between December 1950 - January 1951) - Alpha Team - Mission Successful.
- Operation Bellerophon - February 13th 1951 - Kilo Team - Mission Unsuccessful.
- Operation Icarus - November 1st 1951 - Bravo Team - Mission Unsuccessful.
- Battle of Bear Butte - November 16th 1951 - Echo Team and other Sentinels - Mission Successful.
- Operation Iron Fist - November 28th 1951 - Echo Team - Mission Successful.
- Battle of Adams/Wabash station - December 3rd 1951 - Echo Team - Mission Successful.
- Operation Iron Hand - July 25th 1952 - Echo Team - Mission Successful.
- Operation Kodiak - October 11th 1952 - Echo Team - Mission Successful.
- Operation Charon - November 2nd 1952 - Echo Team - Mission Successful.
- Operation Frozen Fortress - November 11th 1952 - Echo Team - Unknown.
- Assault in Bend, Oregon - December 8th 1952 - Alpha Team - Mission Unsuccessful.
- Eliminate a conversion center in New York City - Between 15 - 20th December 1952 - Charlie Team - Mission Successful.
- Assault on a Chimeran communications array in Montana - December 31st 1952 - Delta Team - Unknown.
- Battle for the Holar Tower - May 17th 1953 - All Sentinels - Mission Unsuccessful.
- Operation Black Eden - June 26th 1953 - Echo Team - Mission Successful.
- Assault on the New York Tower * - July 4th 1953 - All Sentinels - Mission Unsuccessful.
|Alvarez||Unknown||Took part in the Battle of Bear Butte and an assault on the main Chimeran Tower in New York.||Deceased. Killed in a failed mission to destroy the Chimeran Hub Tower, New York on July 4th 1953.|
|Richard Blake||Sentinel Leader||Acting director of advanced tactical ops in SRPA 3.||Deceased. Shot multiple times by a Ravager on June 26th 1953.|
|Stuart Brown||Kilo Team / 1st Leader of Kilo||The Original Leader of Kilo Team.||Deceased. Died during Operation Bellerophon on February 13th 1951.|
|Budry||Unknown||Took part in the Battle of Bear Butte and an assault on the main Chimeran Tower in New York.||Deceased. Killed in a failed mission to destroy the Chimeran Hub Tower, New York on July 4th 1953.|
|Campbell||Alpha Team||Appears in the 'Maiden Voyage of the Sentinels'.||Deceased. Killed by a Chameleon. Date Unknown.|
|Joseph Capelli||1. Alpha Team / 2. Kilo Team / 3. Bravo Team / 4. Echo Team||Appears in R2 and the Comics. Main protagonist in R3||Alive. Dishonored, responsible for killing Nathan Hale.|
|Chu||Unknown.||Participated on an assault on the Main Chimeran Tower in New York.||Deceased. Died during the failed mission of the Chimeran Tower, New York on July 4th, 1953.|
|Cooper||Echo Team||Was part of the Chicago S.A.R. party with Lt. Hale and Capt. Richards||Deceased. Died when a mental blast from an Angel shattered his brain on December 3rd 1951.|
|Russ Dana||Echo Team||Was part of the Chicago S.A.R. party with Lt. Hale and Capt. Richards and an assault on the main Chimeran Tower in New York.||Deceased. Killed in a failed mission to destroy the Chimeran Hub Tower, New York on July 4th 1953.|
|Danby||Unknown||Assaulted on a Conversion Center whilst rescuing Henry Walker.||Unknown|
|Foxtrot Six||Foxtrot Team||Was A Sentinel that fought in the Battle of Hasbro Mining Pit.||Unknown|
|Foxtrot Seven||Foxtrot Team||Was A Sentinel that fought in the Battle of Hasbro Mining Pit.||Unknown|
|Gaines||Echo Team||Took part in Operation Iron Fist.||Deceased. Bitten in the neck by a Hybrid on November 28th 1951.|
|Nathan Hale||Echo Team / 2nd Leader of Echo||The main protagonist and the playable character in RFoM, R2 and Metastasis.||Deceased. Succumbed by the Chimeran virus and converted into Chimera before he was executed by Joseph Capelli on June 26th 1953.|
|Aaron Hawthorne||Echo Team||Appears in R2.||Deceased. Ripped in half at the torso by Daedalus on May 17th 1953.|
|Henning||Echo Team||Was part of the Chicago S.A.R. party with Lt. Hale and Capt. Richards.||Deceased. Died when the fuel tank of his L11-2 Dragon blew up on December 3rd 1951.|
|Hopper||Unknown||Second-in-Command of Captain Kawecki's unit.||Deceased. Took a projectile between the eyes just east of Louisville, Kentucky between April - July 3rd 1953.|
|Jim Jasper||Echo Team||Was part of a recon team with Lt. Hale and Sgt. Kawecki.||Deceased. Killed by Bullseye tag on November 15th, 1951.|
|Jenkins||Unknown||Was Hale's guide whilst rescuing Henry Walker.||Unknown.|
|Marvin Kawecki||Echo Team||A main character that appears all the way through RtGS and RaHitS.||Deceased. Ambushed by New American Republic fighters and killed by a shotgun round to the face on January 11/12th 1954.|
|Lang||Unknown||Took Part in the Battle of Bear Butte and an assault on the main Chimeran Tower in New York.||Deceased. Killed in a failed mission to destroy the Chimeran Hub Tower, New York on July 4th 1953.|
|Laraby||Unknown||Took part in the Battle of Bear Butte.||Deceased. Ripped in half by a Chameleon on November 16th 1951.|
|David LaSalle||Specter Team / 1st Leader of Specter||Provided intelligence and photographs of Chimeran facilities, weapons, creatures and technologies.||Active.|
|Hank Leavitt||1. Alpha Team / 2. Echo Team / 1st Leader of Echo||Original Leader of Echo Team.||Deceased. Died whilst in a Stalker production factory on December 21st 1952|
|Mason||Unknown.||Participated on an assault on the Main Chimeran Tower in New York.||Unknown.|
|Murphy||Alpha Team / 1st Leader of Alpha||Appears in the 'Maiden Voyage of the Sentinels'.||Deceased. Blew himself up with an nuclear bomb to save the other Sentinels. Date Unknown.|
|Obo||Echo Team||Was part of the Chicago S.A.R. party with Lt. Hale and Capt. Richards.||Deceased. Died when an Angel's mental blast shattered his brain on December 3rd 1951.|
|Oshi||Echo Team||Was part of the Chicago S.A.R. party with Lt. Hale and Capt. Richards.||Deceased. Died after being hit by half a dozen Hedgehog Grenade spikes on December 3rd 1951.|
|Pardo||Echo Team||Took part in Operation Iron Fist.||Deceased. Face ripped off by a Fury.|
|Perez||Echo Team||Was part of the Chicago S.A.R. party with Lt. Hale and Capt. Richards.||Deceased. Died when an Angel's mental blast shattered his brain on December 3rd, 1951.|
|Quinn||Unknown||Assaulted an Conversion Center whilst rescuing Henry Walker.||Unknown.|
|Rigg||Unknown.||Participated on an assault on the Main Chimeran Tower in New York.||Unknown.|
|Samson||Echo Team||Was part of the Chicago S.A.R. party with Lt. Hale and Capt. Richards.||Died when an Angel's mental blast shattered his brain on December 3rd, 1953.|
|Tanner||Echo Team||Was part of the Chicago S.A.R. party with Lt. Hale and Capt. Richards.||Unknown.|
|Mike Unver||Unknown||Took part in the Battle of Bear Butte.||Deceased. Blown to pieces by a Stalker during the Second Battle of Tunnel-Through Jaunary 1954.|
|Vedka||Echo Team||Was part of the Chicago S.A.R. party with Lt. Hale and Capt. Richards.||Deceased. Shot in-between the eyes by an Auger round on December 3rd 1951.|
|Venley||Unknown||Part of Captain Kawecki's unit.||Deceased. Killed by a Fury on July 3rd, 1953.|
|Waldron||Alpha Team||Appears in the 'Maiden Voyage of the Sentinels'.||Deceased. A direct hit from Titan fire blew him and the balcony he was on up. Date Unknown.|
|Benjamin Warner||1. Alpha Team/ 2. Echo Team||Second in command during R2.||Deceased. Stabbed to death by Daedalus on May 17th 1953|
|Marshall Webb||Specter Team||Recovered a Chimeran sniper rifle in Kirkwall, Scotland, which became the prototype weapon for the Marksman.||Unknown.|
|Tim Yorba||Echo Team||Took part in Operation Iron Fist and an assault on the main Chimeran Tower in New York.||Deceased. Killed in a failed mission to destroy the Chimeran Hub Tower, New York on July 4, 1953.|
There are known possible Sentinel candidates who didn't survive the events of Project Abraham or etc.
- Captain Frank Gennaro - Committed suicide when his body was burning up due to high metabolism after injected with the Chimeran virus, twice.
- 1st Lieutenant Glenn Khaner - Suffocated by extra tissue which was formed around his brain, lungs and neck cavities.
- Lieutenant Kenneth Danby - Was released to Bryce Canyon, Utah and avoiding his injection at the command of Col. D. Peterson.
- Sergeant Channing Brown - His internal organs liquefied.
- Sergeant Keith Oster - Threatened to kill his doctor who was to inject him with the Chimeran virus and was forced to be killed in self-defense by an attending soldier.
- Private Jordan Adam Shepherd - Mutated into Daedalus after being injected with Pure Chimera DNA.
- Private James Grayson- (Non-canon) Joined SRPA when injected by Chimeran virus by David LaSelle, after being released from prison.
- Alpha Team
- Bravo Team
- Charlie Team
- Delta Team
- Echo Team
- Foxtrot Team
- Haymaker Team
- Kappa Team
- Kilo Team
- Lima Team
- Sentinels were originally called Ghosts as indicated by Damon Iannuzzelli's artwork 
- In Resistance: Retribution's Infected Mode, James Grayson and Roger Cosby were reported to have been given the injection which makes humans turn into Sentinels by Lt. David LaSalle of Specter Team. Given Infected Mode is non-canon, they can't be added to the list of known Sentinels.
- Out of the 41 official Sentinels that are known as of now, 30 are known to have died. All Sentinels with unknown statuses are presumed dead or alive.
- Other possible Sentinels Include: Davis, Cole, Okada, Perkins, Pasco, and Hostler. But cannot be added to the known list due to both possibility that they are human and not enough information are given.