How Did Pilots Navigate In The Dark Before GPS?

It was extremely difficult. The street lighting of towns and major roads would have provided some clues but during World War II, with blackouts over Europe, night bombers flew with a navigator who used the airspeed and compass bearing to plot a course on a map. Over water, some planes were fitted with a calibrated periscope sight that allowed them to measure their motion relative to wave crests and so compensate for a crosswind. Later ‘LORAN’ and ‘Decca’ radio stations were set up around the coast and planes could compare the timing of signals from different stations to triangulate their position.