Apollo Program
The Apollo Program was an early spaceflight initiative of NASA, the space agency of the United States, in the earliest era of manned spaceflight. The program built on work from the earlier Mercury and Gemini programs and concerned itself with the exploration of Luna, Earth's natural moon. The program included a total of 20 serialized missions and a number of test flights, and lead to both the world's first manned landing on the moon (Apollo 11)) and the first such landing on the dark side of the moon (Apollo 20). The Apollo program as a whole, but particularly the outcome of Apollo 1, is the inflection point where the history of the Ecliptic Mariner world begins to diverge from the history of the "real" world. See Wikipedia: Apollo Program for more information on the real-world program.
"It's accurate to within maybe a thousand kilometers. So, depending on what you're doing, it's 'close enough'."
Cassandra Higgs, Life Support Engineer
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Apollo 1
See Also: Apollo 1
Apollo 1 was not the first launch of an Apollo-pattern vehicle, but it was the first successfull crewed flight in the program. It was commanded by Gus Grissom, with Ed White II as Senior Pilot and Roger B Chafee as pilot. In the days prior to the launch, electrical engineers identified a critical safety issue in the on-board electronics, delaying the launch by two weeks. If not corrected, the electrical issue had the potential to start a fire that would not have been easily fought on the launch pad, potentially leading to the death of the crew. The observation lead to correction of both the electrical issues and the provision of new firefighting measures. The flight itself was little more than a simple orbital test flight to prove the spaceworthiness of the Command and Service Module, which was largely successful.
Apollo 2
Apollo 2 was an unmanned test flight which actually took place prior to Apollo 1 and was only retroactively given the designation after the program's chief engineer, Henry A. Storms, died of a brain aneurysm shortly after Apollo 1. Storms was under significant stress to deliver Apollo 1 on time even after the issues with the design were found, and his widow made public comments that the stress was partially or completely responsible for his death. The original flight was an uncrewed suborbital flight which served mainly to test the heat shield on the crew return capsule.
Apollo 3
Apollo 3, like Apollo 2, was an uncrewed test flight retroactively named in honour of the recently-deceased Chief Engineer of the Apollo Program. It launched a severely stripped down payload to prove no capability; rather observations of the physics of the liquid hydrogen fuel were made in order to determine the feasibility of the Saturn IV B-Stage engine restart capability.
Apollo 4
See Also: Apollo 4
Apollo 4 was the first, uncrewed flight of a "full" Apollo stack using the Saturn V rocket and all of the components of the spacecraft, including the Lunar Module. The flight remained in Earth orbit, but tested several key capabilities of the space craft, including re-entry at the full speed of a lunar flight, and the Saturn IV B-Stage engine restart.
Apollo 5
See Also: Apollo 5
An additional uncrewed flight including the Lunar Module, but no command module. The flight served to test the descent and ascent engines of the lunar module and ultimately provided the data needed to approve the LM for human flight.
Apollo 6
See Also: Apollo 5
An attempted flight of an uncrewed Apollo vehicle on a Saturn V rocket which was to demonstrate trans-lunar injection and direct-return abort. Three engine failures resulted in the failure of these tests, but flight controllers were able to recover the craft using SM engines and return the craft for de-orbiting along a profile similar to that of Apollo 4. Despite the issues, the flight provided the data needed to human-rate the Saturn V.