Let's Go to the Moon this Christmas - 10

SPLASHDOWN!

I couldn't find a video of the Apollo 8 splashdown, so here's one they did later - Apollo 15;



So the mission went almost perfectly. A good thing too.
In November 1970, it must have preyed on Jim Lovell's mind that had the Service Module exploded on Apollo 8, as it did on his later flight Apollo 13, there would have been no hope of recovering control and returning to Earth. Apollo 13 only made it back because they had the Lunar Module still attached and were able to use it's engine to power back to Earth before the crew all died of exposure or more likely, asphyxiation.

In the case of Apollo 8 though, once the mission had slowed from the free return trajectory to orbit the Moon, there was only one way back; firing the Service Module engine successfully.
The mission was a bold and courageous undertaking. There was no back up plan, no hope of rescue and no experience to draw upon. The Apollo 8 mission emboldened NASA and made the Moon landing in 1969 a possibility - it converted hope into experience.