Did you read the messages and letters posted by PeaRidge? By the meaning contained in them, it certainly looks like this interpretation of events is just wrong.
If those messages and letters are correct, it would appear to be just a fluke of time that the Union didn't start firing first. They were certainly in a position to do so, and seemingly had every intention of doing so as well.
It would appear the Union deliberately sent a hostile force to engage the Confederates and only refrained because the bombardment of Ft. Sumter had already started, and would therefore better serve the propaganda interests of the Union.
This entry in the ship's log of the USS Supply is for the night prior to the events at Fort Sumter. It documents an invasion force landing in Florida, in violation of the existing armistice, before the events in South Carolina.
USS SUPPLY SHIPS LOG - APRIL 11, 1861 pg. 210 OPERATIONS IN THE GULF OF MEXICO.
Abstract log of the U. S. sbip Supply, January 9 to June 14, 1861, Commander Henry Walke, commanding.
April 11. -- At 9 p. m. the Brooklyn got Underway and stood in toward the harbor, and during the night landed the troops and marines on board, to reenforce Fort Pickens.
210 OPERATIONS IN THE GULF OF MEXICO.
Abstract log of the U. S. ship Supply, January 9 to June 14, 1861, Commander Henry Walke, commanding.
January 9, 1861.—Off Warrington navy yard, Pensacola, Fla. From
meridian to 4 p. in.: Sent a boat to Fort Barrancas to assist the troops
in moving to Fort Pickens.
January 10. -- From 4 to 8 a. in.: Stood down for Fort Pickens. From
8 to meridian: Assisting the work at Fort Pickens. From meridian to 4
p. in.: Sent boat to assist in removing powder and different articles from
the Barrancas to Fort Pickens. From 4 to 8p. in.: Men and boats assist-
ing in getting Fort Pickens in a state of defense; also sent to Fort
McRee.
January 11. -- An officer and boat’s crew sent to cooperate with the
garrison of the fortifications. A number of men sent to assist the gar-
rison of Pickens and destroy the powder at Fort McRee.
January 12. -- From meridian to 4p.m.: The navy yard,marine bar-
racks, and hospital surrendered and hauled down the American flag to
the State troops of Florida. From 4 to 8p. in.: Stood out of the harbor
and anchored.
January 13. -- Was taken in tow by the Wyandotte and stood in for
the harbor under flag of truce. Received on board the family of Lieutenant Irwin.
January 14. -- Received men from the hospital and men from the yard
and baggage of the officers of the yard; also their furniture.
January 15. -- Received on board the families of the late forward offi-
cers of the navy yard [Pensacola], and their baggage.
January 16. -- At 7 a. m. got underway and stood out of the harbor
[Pensacola].
February 4. -- At 2:30 p. m. arrived at the navy yard, New York.
March 6. -- At 1 p. m. ship weiit in commission, Commander A. Gibson
in command.
March 15. -- At 10 a. in. got underway and stood down the harbor
[New York].
April 7. -- Came to anchor in the harbor of Pensacola.
April 11. -- At 9 p. m. the Brooklyn got Underway and stood in
toward the harbor, and during the night landed the troops and marines
on board, to reenforce Fort Pickens.
April 16. -- At 5 p. m. steamer Atlantic arrived with troops and munitions of war for Fort Pickens. During the night 300 troops were landed on Santa Rosa Island by the boats of the squadron.
April 17. -- Lieutenant J. R. M. Mullany took command of this vessel. Boats of the squadron employed landing troops and munitions of war.
April 18 and 19. -- Boats from squadron employed landing munitions
of war and army stores from Atlantic on Santa Rosa Island.
June 14. -- Standing into New York.
Abstract log of the U. S. S. Wyandotte, January 12 to May 16, 1861, Lieutenant O. H. Berryman, commanding.
January 12, 1861. -- At 2 p. m the American ensign and flag-officer’s flag were hauled down at the navy yard.
January 14. -- Florida forces hoisted the American flag with lone star.
January 18. -- Sent six marines to Fort Pickens.
January 20. -- At 11 a. in. six marines and ten seamen volunteered and went on shore to assist at Fort Pickens. From 8 to 12 midnight: Sent ten men to Fort Pickeus to assist in mounting guns.From our good friend nolu chan
At the time, Union forces were under orders not to fire on Confederates unless attacked.
And, as Lincoln announced ahead of time to South Carolina's governor, ships sent to Fort Sumter were only intended to resupply, not to reinforce the garrison, so long as things remained peaceful.
But, given a choice, Confederate leaders did not want peace nearly as much as they wanted to force Sumter's surrender, and if that meant war, then so be it.
Jefferson Davis immediately ordered final preparations to assault Fort Sumter.
Finally, it's important to remember that no Confederate soldier was killed directly in battle with any Union force until the Battle of Big Bethel, June 10, 1861 -- months after the Confederacy first provoked, then started and formally declared war, while sending military aid to pro-Confederates in the Union state of Missouri.