Conversation so far:
Which war broke out in William H. Seward's lifetime?
On April 12, Charleston's batteries began firing on Sumter, beginning the Civil War.
What did William H. Seward do in the Civil War?
William H. Seward sent Lincoln a memorandum on April 1, proposing various courses of action, including possibly declaring war on France and Spain.
Why did William H. Seward suggest declaring war with France and Spain?
William H. Seward's firm stance against foreign intervention in the Civil War helped deter France from possibly gaining the independence of the Confederate States.
Did William H. Seward communicate with Lincoln other times during the war?
Seward drafted a strong letter for the American Minister in London, Charles Francis Adams, to read to the Foreign Secretary, Lord Russell. Seward submitted it to Lincoln.
Anything else interesting with William H. Seward and Lincoln?
Seward hinted to the commissioners who had come to Washington on behalf of the Confederacy that Sumter would be surrendered. Lincoln was loath to give up Sumter.
Anything else about Sumter and William H. Seward besides William H. Seward hinting to the commissioners who had come to Washington on behalf of the Confederacy that Sumter would be surrendered?
Lincoln faced the question of what to do about Fort Sumter, held against the will of South Carolinians. Seward recommended that an attempt to resupply Sumter would be provocative.
What happened with the South Carolinians at Fort Sumter?
It remained in Confederate hands until it was evacuated as General Sherman marched through South Carolina in February 1865.

Question: What was Lincoln's final decision about Sumter?
Self-contained rewrite: What was Lincoln's final decision about Fort Sumter during the Civil War?