I had written a detailed post on Benjamin Lincoln, Anthony Wayne, the Pennsylvania Line, the 4th Division of the Main Army, both its brigades, and other supernumerary units. Unit histories, uniform notes, principal officer bios, everything.
I deleted two lines, then reconsidered and closed the edit window without saving and reopened it, thinking I would have the page before I had made any changes.
It was entirely blank. Everything I've written and carefully saved for weeks. All the links to my reference materials, all the written and rewritten passages.