[AlmaKing]

The Confederacy gave the Union multiple chances to peacefully leave Fort Sumter. The Union refused. Lincoln could have backed down several times, if he truly wanted a peaceful resolution. But, he went ahead with re-supply.

[rockrr]

Diplomacy at the point of a gun eh? The fact is that the installations (such as Sumter) belonged to the federal government - not the state of So. Carolina. If THEY had wanted a “peaceful resolution” they would not have acted so belligerently.

[BroJoeK]

AlmaKing: "The Confederacy gave the Union multiple chances to peacefully leave Fort Sumter.
The Union refused. Lincoln could have backed down several times, if he truly wanted a peaceful resolution.
But, he went ahead with re-supply."

Sure, but any threats against a nation's military forces in their own bases (i.e., Pearl Harbor, 1941) are provocations for war.
Any military assault on those forces is an act of war -- at Fort Sumter in 1861 just as at Pearl Harbor in 1941.

The Confederacy launched war against the United States at Fort Sumter, just as surely as the Japanese did at Pearl Harbor in 1941:

"I ask that the Congress declare that since the unprovoked and dastardly attack by Japan on Sunday, Dec. 7, a state of war has existed between the United States and the Japanese empire."

[Bubba Ho-Tep]

The Confederacy gave the Union multiple chances to peacefully leave Fort Sumter. The Union refused. Lincoln could have backed down several times, if he truly wanted a peaceful resolution. But, he went ahead with re-supply.

Hey, I want your house. If you don't leave, you'll force me to beat you up. It will be your fault because you could have backed down, but instead you had groceries delivered.