I agree with Slingshot; so many years discriminating and should have been going all metal, but I must say back when I started there was still an abundance of relics and thought it was the way to go and didn't factor in the deeper stuff. Anyway here's my story.
There was a heavily wooded area with undergrowth so thick you couldn't even crawl through it, much less swing a machine, and was located in the middle of a major CW battle. Always had my eye on it and kept going back thinking for some reason it would improve, but we know how that goes. Finally a couple of years ago a development company started clearing it out for a commercial site, but you really couldn't tell at first because they cut a road right to the middle and started working their way out instead of coming from the outside in. By the second day I finally saw the heavy equipment on my way home from work and knew what was going on. Tired from work I didn't go straight to the site but promised myself I would go the next day (word of advice, never make these promises and go no matter how tired). I went the next day as planned and by that time they were just starting to put up the Posted signs and asking relic hunters to leave. Talked to a few guys who had hit the spot the first two days. Turns out the area was a field hospital that was still evident up through the 1930s until someone pushed dirt over it but not sure why. The first two days they coincidentially just scraped off the fill-in down to the original site and the guys who did hunt it before it was posted had stories to tell that just made me ill. Plates and belt buckles galore from both sides, not to mention the abundance of buttons and other desired relics - believe me they showed me what they found. They said it was obviously a virgin site and was like hunting back in the day when detecting first started; hardly any trash - just relics. I still kick myself for not going when I first saw what was happening.
Like the thread states, a missed opportunity and a strong lesson of never promising myself to go hunting the next day. Its getting harder to stay ahead of development, so go guys whenever the opportunity presents itself.