A quote from the other thread posted by the thread starter of this thread
You realy have no clue what you are talking about. France signed the Valletta Treaty in 1995, and that means I can use a detector on my own land, it even means I can use a detector on other peoples land if I have their permission. The only exception is if the land is protected, like the beaches of Normandie, or the wwI battle fields in the north. Also sites like Roman sites are protected, but I can search my own land with a metal detector, and I dont need any permission of anybody to do so.
By the way; nice avator of the church in St Mere de Eglise, I can see the church and village from my window. That is where I live, and detect.
And another from the same thread
Indeed, my understanding is that all relics from WW1 and WW2, regardless of where or how they are found, are now property of the French state. Removal of them from the location you find them is classed as theft from the state and, as already been pointed out, subject to hefty fines.