The original meaning of the word ‘curfew’ was ‘to cover the fire’ and our English word curfew comes from the French ‘couvre feu’
In medieval France and many other European countries, a bell would ring every night at 8 or 9 pm, a signal to remind people to cover or put out candles and fires.
Why? Because there were no fire alarms and no hotline to the fire services, so enforced extinguishing of candles prevented the spread of fire within communities where homes were often built using very flammable timber.
Town employees would also have the job of walking the streets and ‘covering’ the street lamps to put them out.