With relatively cheap and available night vision devices, the military and police have quickly become dependent on technology. Heck, you can’t even break into a hardware store without some day/night surveillance camera filming the whole thing. We have even forgotten some of the things routinely taught in the Army as late as the 80’s.
Even though they lacked our technology and medical knowledge, the ancients spent a lot of time in the dark. Since prehistory, humans fought and hunted in the dark. Warriors sought every advantage and many groups developed night fighting skills.
One of the first recorded accounts of night combat (some say the first special operations mission) was the biblical account of Gideon. After running a selection and assessment course, he conducted a night attack on an entire army. Carefully using light and noise to cause confusion, he persuaded the Medianites to help the effort by killing each other. In true SF fashion, there were no friendly casualties, but Gideon’s commando team was exhausted carrying away the spoils of war.
The human eye works much like a digital camera. The pupil is a lens which focuses light on to receptors in the retina. The brain processes this data and turns it into the experience we call human vision. There is an incredible amount of processing which goes on in the brain.