But why did the South fire on Sumter to begin with?
I've been pondering that question (once again) since Tuesday, and as near as I can tell it was because they were gullible @ssholes.
Thinking that they had the ability to weigh pros and cons of doing such a thing, I can conceive of only one calculation which puts firing on Ft. Sumter into the "pro" category.
Now someone had mentioned to me before, and perhaps it was you, that some states were having mixed feelings about secession and were thinking about re-joining the Union, and so Jeff Davis needed such an incident to galvanize them into staying the course, and perhaps to convince others to also join them.
Perhaps this is what they were thinking, but one of the Cabinet members (and I forget who) told them in no uncertain terms what would very likely happen, so it cannot be argued that they weren't and clearly warned.
What did they expect to happen when you Humiliate a much larger and more powerful adversary? Especially when you consider that they are just looking for an excuse to kick your @ss anyway?
Hubris, is probably the most intellectually honest reason for why they did it.