Daylight helps you just as much as your enemy. We've got plenty of cutting edge night vision and thermal imaging devices for humans and radar on vehicles. The Army's 160th helicopter regiment can fly nap of the earth on a moonless night. Satellite-based Synthetic Aperture Radar can pickup human sized objects during a pass and can switch to sub-centimeter resolution in finer modes. If anything, the military prefers fighting at night because of the advantage it holds.