[95]

Proposed constitutional amendment
On March 2, 1861, Congress approved an amendment to the United States Constitution that would shield "domestic institutions" of the states, including slavery, from the constitutional amendment process and from abolition or interference by Congress. The proposed amendment was submitted to the state legislatures for ratification. Commonly known as the Corwin Amendment, it was never ratified by the requisite number of states.

States admitted to the Union
Three new states were admitted to the Union while Buchanan was in office:

Minnesota – May 11, 1858[96]
Oregon – February 14, 1859[97]
Kansas – January 29, 1861
Post-presidency (1861–1868)
Buchanan in his later years. c. mid-1860s
The Civil War erupted within two months of Buchanan's retirement. He supported the Union, writing to former colleagues that, "the assault upon Sumter was the commencement of war by the Confederate states, and no alternative was left but to prosecute it with vigor on our part."[98] He also wrote a letter to his fellow Pennsylvania Democrats, urging them to "join the many thousands of brave & patriotic volunteers who are already in the field.