In the 12th century, after William the Conqueror, the French ruled England. At the time, when darkness fell, homes would of course burn candles at home to light their residences. The problem was that having so many candles and fires burning in the hearth was dangerous, and homes would sometimes burn. The larger problem was that all homes in villages would be made of wood and often built close together. So, if one house caught fire, it was common for the flames to leap to the next house -- and keep leaping from home to home, until entire villages would regularly be wiped out.
To combat the problem, the Norman rulers imposed a law that no fires could be burned after a certain hour, and a bell would ring throughout town to note that all fires had to be covered and the fires put out.
The Norman, as noted, were French. And the verb in French for cover is "couvrir". And the word for fire is "feu." So, what you had was a bell ringing to "couvre feu."
Which became ringing in curfew.
Tomorrow, we will be taking up basket weaving. Though interested in bread making should see Mrs. Halifax in Room 205. I believe she still has space to sign up...