I thought I read that there were two giant ones that hadn’t been found. I know that every year an unlucky French farmer or two ‘discovers’ an artillery shell when he’s plowing his fields. I know there are some areas that are still no-go zones.
I often watch “Mudlarking” videos on the Thames River. Several times they have had to call demolition teams to detonate munitions found.
I used to work for a company that was based in New Jersey on the grounds of an old WWI munitions plant. Even as of a few years ago, they would occasionally find unexploded shells when they dug for construction.
Yeah, those two have been found. They know exactly where they are. Unfortunately, residences and farms have been built over them in the intervening decades and it is thought that any attempt to disarm the charges will cause them to detonate as the explosives have likely gone unstable.
They’re hoping that they will degrade to the point where they go inert in the next few decades.
And yes, the Iron Harvest is a thing.
https://en.wikipedia.org/wiki/Iron_harvest
WW1 will likely still be killing people in Europe a half-century from now, if not longer.
And that’s in Belgium - in France... they’re thinking WW1 may potentially still be killing people for 300-700 more years and they still have no-go zones, La Zone Rouge:
https://en.wikipedia.org/wiki/Zone_Rouge