UXO is a hell of a thing.
And the last Revolutionary War veteran died in 1866. (The year after our Civil War ended, in case you don't know much American history.)
I don't know if there's a more recent example of Civil War UXO causing injuries, but here's a news article about a man killed in February 2008: http://www.foxnews.com/story/2008/05/02/virginia-man-killed-...
As a result, even up to the mid-1990s, when I was there, it was not unusual to see a block or two closed off periodically because someone digging had found unexploded ordnance there. And due to the chemical weapons work, these discoveries were more disconcerting than usual, because who knew if it was just a standard high-explosive shell or something loaded with mustard gas, or worse?