At the height of the Space Race, after the Soviet Union had stolen a march by launching the first satellite as well as the first man into orbit, the United States decided to set their targets on the Moon.
The famous Apollo 11 landing in 1969, which marked the culmination of this, did not happen in isolation. It was the culmination of years of effort, involving unmanned probes that orbited and landed on the Moon, as well as manned craft that orbited the Moon without landing.
The unmanned Lunar Orbiter missions in 1966 and 1967 prepared the ground for Apollo by mapping the surface of the Moon from space. One byproduct of this is a remarkable series of photos from Lunar Orbiter I, which are the first pictures of the Earth taken from beyond the Moon. Via Earth in 1966.