A military assault on Union troops in Union Fort Sumter was an act of war, regardless of how many were killed.
Indeed, many more would have died, had Maj. Anderson decided to seriously fight.
As it happened, two soldiers lost their lives directly as a result of the action.
And least anybody doubt the Confederacy's intentions, they soon formally declared war on the United States, on May 6, 1861.
I think in DL's world, formal declarations and actions mean nothing. The Declarations of Secession say their cause was slavery. DL says no. The Confederacy tried to murder those at Sumter, DL says that since they were bad shots it should have been overlooked. The Confederacy declared war on the US. Never been mentioned by DL. DL says even though it was war and the objective was preservation of the Union, that the north should've immediately gave up after stiff resistance.
DL is definitely in the running as being closest to 180 degrees away from logic, common sense, knowledge of human reaction to events, and just a general knowledge of how history flows in these situations.