On April 19, Lincoln issued his proclamation blockading Southern ports. It provided that “a competent force will be posted so as to prevent entrance and exit of vessels” from the ports of the states in rebellion. Then, to make the proclamation official, he signed this document, authorizing “the Secretary of State to affix the Seal of the United States to a Proclamation setting on foot a Blockade of the ports of the States of South Carolina, Georgia, Alabama, Florida, Mississippi, Louisiana, and Texas.” The seal was affixed to the blockade proclamation, which was announced that day.
It was a de facto declaration of war by the Union against the Confederacy.
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