Did Davis know that ordering an attack on Sumter would start a war? Yes.
"Mr. President, at this time it is suicide, murder, and will lose us every friend at the North. The firing upon that fort will inaugurate a civil war greater than any the world has yet seen." [Robert Toombs speaking to Jefferson Davis in confederate cabinet meeting, 11 April 1861, quoted in W. A. Swanberg, First Blood: The Story of Fort Sumter, p. 286]
Was Fort Sumter federal property? Yes.
"South Carolina had ceded property in Charleston Harbor to the federal Government in 1805, upon the condition that the United States... repair the fortifications now existing thereon or build such other forts or fortifications as may be deemed most expedient by the Executive of the United States on the same, and keep a garrison or garrisons therein (The Statutes at Large of South Carolina, Volume V, page 501).
From the South Carolina legislature:
"Committee on Federal Relations
In the House of Representatives, December 31st, 1836
"The Committee on Federal relations, to which was referred the Governor's message, relating to the site of Fort Sumter, in the harbour of Charleston, and the report of the Committee on Federal Relations from the Senate on the same subject, beg leave to Report by Resolution:
"Resolved, That this state do cede to the United States, all the right, title and claim of South Carolina to the site of Fort Sumter and the requisite quantity of adjacent territory, Provided, That all processes, civil and criminal issued under the authority of this State, or any officer thereof, shall and may be served and executed upon the same, and any person there being who may be implicated by law; and that the said land, site and structures enumerated, shall be forever exempt from liability to pay any tax to this state.
"Also resolved: That the State shall extinguish the claim, if any valid claim there be, of any individuals under the authority of this State, to the land hereby ceded.
"Also resolved, That the Attorney-General be instructed to investigate the claims of Wm. Laval and others to the site of Fort Sumter, and adjacent land contiguous thereto; and if he shall be of the opinion that these parties have a legal title to the said land, that Generals Hamilton and Hayne and James L. Pringle, Thomas Bennett and Ker. Boyce, Esquires, be appointed Commissioners on behalf of the State, to appraise the value thereof. If the Attorney-General should be of the opinion that the said title is not legal and valid, that he proceed by seire facius of other proper legal proceedings to have the same avoided; and that the Attorney-General and the said Commissioners report to the Legislature at its next session.
"Resolved, That this House to agree. Ordered that it be sent to the Senate for concurrence. By order of the House:
"T. W. Glover, C. H. R."
"In Senate, December 21st, 1836
"Resolved, that the Senate do concur. Ordered that it be returned to the House of Representatives, By order:
Jacob Warly, C. S."
continued....