In this case, it was due to a web-shooting Hill Giant. (N.B., really? Hill giants shoot webs? Okay then, will be prepared next time. [Technically, it was a Hill Giant that looked like a python, but had a shell, so there's that going for it...])
Anyway, I was down to my last dwarf, and he was apparently a smear on the floor, so I gave up, for now. Next step, find that embark and salvage it for the glory of dwarf-kind and the mountainhome.
Unfortunately, after going to "Start Playing", and choosing the Dwarf World I was in, I'm dropped back into the embark selection screen. Is there a short-cut to find where I'd previously embarked? How can I get back to where I was?
Long story short. I'd embarked, failed (Losing is FUN), and want to get back to the same spot. How can I do that?