What was President Lincoln's first response to the situation at Fort Sumter?
Lincoln's first response, after hearing of the situation, was to re-supply the garrison stationed at Fort Sumter (with food/water, not men).
Lincoln made this explicitly clear, but the Confederates bombarded the fort anywho.
I believe this is precisely what Lincoln wanted, because it:
a) makes the Confederates look like the bad guy, and thus the aggressor.
b) gives the Union a valid reason to then attack the Confederacy.