James Russell Soley, Professor U. S. Navy, Confederate Military History, a library of Confederate States Military History: Volume 7.1, The blockade and the cruisers
Clement Anselm Evans, Ed.

It was natural, in view of the inadequacy of the force, that foreign governments should look at the measure with suspicion, and should watch its execution with careful scrutiny. Commercial communities abroad doubted the seriousness of the undertaking, because, in their ignorance of the energy and the resources of the Government, they doubted its feasibility. An effective blockade on such a scale was a thing unprecedented, even in the operations of the foremost naval powers of the world. It seemed to be an attempt to revive the cabinet blockades of half a century before, when England and France laid an embargo upon each other's coasts, and captured all vessels at sea whose destination was within the proscribed limits; and when Spain interdicted commerce with the northern colonies in South America, and as a matter of form, kept a brig cruising in the Caribbean Sea.

No time was lost in announcing the intentions of the Government. On the 19th of April, six days after the fall of Sumter, the President issued a proclamation declaring the blockade of the Southern States from South Carolina to Texas. On the 27th the blockade was extended to Virginia and North Carolina. The terms of the proclamation were as follows

Now therefore I, Abraham Lincoln, President of the United States . . have further deemed it advisable to set on foot a blockade of the ports within the States aforesaid, in pursuance of the laws of the United States and of the Law of Nations in such case provided. For this purpose a competent force will be posted so as to prevent entrance and exit of vessels from the ports aforesaid. If, therefore, with a view to violate such blockade, a vessel shall approach or shall attempt to leave any of the said ports, she will be duly warned by the commander of one of the blockading vessels, who will endorse on her register the fact and date of such warning, and if the same vessel shall again attempt to enter or leave the blockaded port, she will be captured, and sent to the nearest convenient port for such proceedings against her, and her cargo as prize, as may be deemed advisable.