Part 1: intro to series, and the events of AS-204, later known as Apollo 1
This TL isn't focused on being purely technical and 100% accurate, it's all more for fun
Before I start, creds go to the creators of boldly going, eyes turned skyward for inspiration, and @Antiantiperson on Twitter for mission patches.
some ideas for vehicles come from Eyes Turned skyward, primarily the Saturn IC, however, this may change in the future...
Rewriting history Part I "Under the Umbrella Of Fire"
Apollo 1 astronaut Virgil I. "Gus" Grissom leads fellow crew member Roger B. Chaffee across the Crew Access Arm to the White Room to enter the Apollo Command Module (CM). The third crew member Edward H. White followed shortly after.
January 27th, 1967
The crew: Gus Grissom, Edward H. White II, and Roger B. Chaffee, boarded their Apollo I capsule in anticipation of the upcoming tests which were due to be performed by the crew in the next couple of hours that they would spend inside of the command module. the crew experienced constant communication issues between them and the control centers in the blockhouse and the ACE room due to static caused by an unidentified microphone that was left out in the open. At 6 pm the instruction was given to Grissom to proceed with the simulated hot fire test of the reaction control system of the service module, this test was completed successfully despite the communication issues, which from there continued further. After the test, it became evident to Chauvin that, at simulated launch time, when the umbilicals would disconnect from the spacecraft the hardline communications link would be lost, so a switch to just S-band communications was in order, after a small pause in communications the crew was back on, firstly testing each one of the astronaut's communications status, after going through all 3 of the astronauts there was still no solution to the irritating sounds of microphone static.
The count down was approaching t-10 minutes and the issues were still at large, just the communication was a struggle in itself, the already agitated Gus complained "How are we going to get to the Moon if we can't talk between two buildings", White chimed it letting Grissom know "they can't hear a thing you're saying". The astronaut's frustration was shared by the control centers, the entire afternoon was spent attempting to fix the communication issue and the simulated lift-off was approaching fast. It was becoming evident that this simulated launch may not be happening today in full.
At 6:30:55 pm the engineers who were monitoring spacecraft systems noticed a voltage spike in one of the electrical busses amongst other strange electrical signals, a mere 10 seconds later one of the astronauts, presumably Grissom over the comms, yelled: "fire" followed by White "Hey! we got a fire in the cockpit" evidently the fire started from the side that Grissom was on and the second to notice was White. The quick reaction of Commander Gus Grissom resulted in the hatch being blown right off the command module as he pulled the pin, the hatch was blown quite the distance away, luckily no ground crew was injured by the hatch, and the ground crew rushed to help the crew of Apollo 1, pulling them out of the command module within a matter of seconds, only Gus and White suffered minor burns on their faces, and some of the ground crew had also inhaled quite a substantial amount of smoke and received 1st to 2nd-degree burns on arms and hands.
The crew was away from the command module and the fire stopped quickly as the Earth's atmosphere rushed into the 100% oxygen environment, snuffing the fire out, the capsule had been scorched quite well nonetheless. This was a stroke of brilliant, and at the same time, horrible decision-making by NASA, it was initially thought to be a good idea not to include any explosive bolts for this test, it was deemed too dangerous for the ground crew and completely unnecessary as NASA was sure no accidents could happen, yet it became a given gift for the crew, saving them from an incident which could of very well cost them their lives.
The crew of Apollo 1 had almost predicted their disaster after they jokingly posed praying upon their spacecraft as they believed it was dangerous, with all of the flammable material, exposed wire, and weird, inward opening hatch...
And sadly they were correct, this was a horrible moment for NASA but it could have turned out much worse, this mission delayed the apollo program by 14 months, while NASA prepared and tested the new Apollo block II spacecraft which would be a much bigger upgrade over the Block I, less flammable equipment and most importantly the atmosphere was changed to an oxygen/nitrogen mixture, which was much closer to what was encountered at sea level.
The Apollo capsule was taken away for investigation and the crew went in for medical checkups, the exact cause wasn't discovered at first and is still not entirely known about to this day, however, it is well assumed that it was an electrical issue, presumably due to an electrical spark to the left side of Grissom, this spark quickly turned into a large fire due to the 100% oxygen atmosphere within the command module. further investigation was done to realize, analyze and subsequently make the design changes to create a safer version of the Apollo command module, removing all the fire hazards, making a new hatch, and changing the atmosphere. The next Apollo flight is scheduled to be Apollo 4, the first uncrewed test flight of the Saturn V.
This concludes my first post here, feel free to give constructive criticism. thank you for reading!