Slight thread drift...
TD67 and his dad went to the Western Front area a coupla years back and got talking to a local, who told us that the farmers there are regularly crunching into stuff from the Great War in their ploughs. They have a set procedure for the local bobby to come collect it.
One incident he related, however, was slightly more amusing... young couple spotted a likely copse on a summer`s day and got at it behind said stand of trees. Mission interrupted by stinging sensation in his knees and elbows and all over her back. Went to local hospital, doctor recognised contact with mustard gas... The local authorities went to investigate and it turns out a mustard gas shell had been parked right near where they were since the War and had rusted through, leaching some of the noxious substance into the surrounding soil.
Bet that dampened their ardour...