- "The Alpha needs anonymity. A place where no one will think to look for him."
- "I believe I know exactly the place."
- "Show me."
- —Director in Don't Say It
Blood Gulch is a canyon that Project Freelancer used to test the abilities of their Freelancers in a simulated battle. The canyon also held a second purpose: to keep the Alpha A.I. in a secure and hidden location to prevent anyone from finding him. However, due to the events of the Blood Gulch Chronicles, Project Freelancer had to relocate most of the simulation troopers there to keep Alpha's location a secret.
During the entirety of The Blood Gulch Chronicles, when calling Vic, Church will start out by saying "This is Blood Gulch Outpost Alpha," while Sarge, and anyone else on Red Team will refer to red base as "Blood Gulch Outpost Number One." This could be due to the fact that the Red and Blue teams are commanded by the same person. While there are only two bases in the canyon, they are both variations of "first" on a list of bases in Blood Gulch. Also, it appears that most of the canyon's soldiers, except for perhaps Sarge and Caboose, hate the canyon, openly questioning the strategic value of such a worthless location.
In Reconstruction, Washington goes there and refers to Blue base as Outpost 1-A and 1-B, which are the Blue and Red bases. In the Red vs. Blue civil war/training simulation, the Red Team won this base because, after all the soldiers except Sarge, Lopez, and Sister were transferred (Sarge was in actuality AWOL, though he would later leave and be transferred to Valhalla). Lopez would later join Sarge in Valhalla while Sister remained alone in Blood Gulch after Lopez failed to kill her like he had so claimed.
After the final battle with the Meta in n+1, Epsilon later got trapped in the capture unit. So during this time, he began to relive the events of The Blood Gulch Chronicles with his memories of the Reds and Blues in a mental image of Blood Gulch. However, he was later removed from this "Blood Gulch" when the Reds, Blues, and Carolina, rescued him in Hate to Say Goodbye. Later, after the events of Season 10, the Reds and Blues were intended to return to Blood Gulch, however, their ship crashed before they could arrive.
In The End is Near, a momentary view of Blood Gulch reveals that since the Reds and Blues departed, the canyon has entered a state of mild degradation; the greenery has long since rotted away, and the abandoned bases have fallen into disrepair and filth. Sister still resided there, joyful to learn her brother was alive.
Blood Gulch reappears in Season 15 as the first location that Dylan Andrews travels to for her investigation of the Reds and Blues. While there she meets both Sister and V.I.C., the latter of which agreed to assist with the investigation on the condition that she delete him after three "wishes." It is revealed through her investigation that Blood Gulch is based on a previous simulation outpost known as Desert Gulch.
Sister later leaves Blood Gulch and travels to Chorus for business, before reuniting with the Reds and Blues on Earth during Epilogues. With the Reds and Blues on Chorus after the events of Singularity, Blood Gulch is currently abandoned.
- It is generally implied that the bases are much bigger than the Halo game engines depict, with characters being written as having bunks the base having mess halls, and storage areas. The bases also have tools and equipment, such as having shovels to dig graves (Season 2), finding ice cream (Season 4) and holding parties in the base (Reconstruction).
- Blood Gulch is represented by Coagulation in the Halo 2 engine, and by Bloodline in the Halo 2 Anniversary engine. Epsilon's mental image of Blood Gulch is represented by Hemorrhage, a map created within Forge World, in the Halo: Reach engine. In Halo 5: Guardians, it is represented by a heavily customized version of , an open canvas map meant for Forge, similar to Forge World.
- Epsilon's memory reconstruction of Blood Gulch is openly called out as different from the original canyon. Due to the fact the map is represented by Halo: Reach's Hemorrhage, it is not an actual box canyon; the Blue base is situated next to a small open shoreline, while the Red base is situated next to an oddly out of place giant steel wall, (which closes Hemorrhage off from the rest of Forge World). The steel wall was the subject of the miniseries Where There's a Will, There's a Wall.
- It is believed Rooster Teeth started filming on this map since it is one of the most popular Halo maps in history, as well as the fact it was one of the two vehicle-capable maps in the original Halo: Combat Evolved title. It is also believed they used Red team and Blue Team since those are the colors of the two bases and the only teams for Capture the Flag, a popular game type.
- Its status as Outpost 1 could be because the Alpha is stationed here. The Alpha being here (and a Blue) could be the reason blue base is Blood Gulch Outpost Alpha.
- For the description of Hemorrhage, it states "Many call this curious gorge their grave, but the early inhabitants only left these outposts behind in memoriam." This could be a reference to Red vs. Blue as both teams haven't been to Blood Gulch in many years.
- Blood Gulch has the most appearances out of all the locations in the series, with Sidewinder having the second most and Zanzibar having the third most.
- Although most of the main cast state that they hate Blood Gulch, it's revealed that they wanted to head back there after the events of Season 10. In n+1, Epsilon uses the canyon as the basis for a 'good' memory, though he may be referring to his time spent with the other members of the Red and Blue teams in that context.
- As stated by Donut in Worst Laid Plans, the Reds and Blues were originally supposed to return to Blood Gulch before their ship crashed after the events of Season 10.
- It was heavily implied that Crash Site Bravo was Blood Gulch in Don't Say It; however, in Season 11, it was revealed to be a location on Chorus, an entirely different planet.
- In Halo: The Master Chief Collection, there is an achievement called Red vs. Blue that is unlocked when the player wins 10 matches on the Halo 2: Anniversary map "Bloodline" (A remake of Coagulation in the original Halo 2).
- Originally it was assumed the Reds won Blood Gulch as Lopez thought he had killed Sister by choking her, but later it was revealed that she had survived. As Sister is a member of Blue Team and the only soldier left in the canyon, the Blues become the actual winners of Blood Gulch.
- The Project Freelancer Saga is currently the only story arc where Blood Gulch doesn't make an appearance at all
- Although the final location shown in the arc was originally depicted to be Blood Gulch, it is later retconned to being Crash Site Bravo, so this does not count.
- Since the end of Season 5, two new vehicles have shown up in Blood Gulch. In The End is Near, a flame Warthog can be seen at Red Base. In The Chronicle, another Warthog can be seen at Blue Base.
- Blood Gulch (Halo CE) (Seasons 1-3)
- Coagulation (Halo 2) (Seasons 3-5)
- Hemorrhage (Halo Reach) (Season 9)
- Barrens (Halo 5) (Season 15-17)
- Bloodline (Halo 2: Anniversary) (Season 13, 16)
|Project Freelancer: 1-Blood Gulch: 1A 1B · 9-Sidewinder · 17-Valhalla: 17A 17B · 25-Rat's Nest: 25A 25B · 48-High Ground: 48A · ?-Desert Gulch|
|Federal Army of Chorus: 22-F.A.C. Outpost 22 · 37-F.A.C. Outpost 37|
|Unnamed: Battle Creek · UNSC Wind Power Facility · Danger Canyon · Timberland|