Was there something that happened three days before that Proclamation, on April 12th, that might have justified such a drastic (but quite constitutional) step?
Why pick April 12th? Why not January 9th and The Star of the West? Or why not October 16, 1859 and the Harper’s Ferry raid? John Brown was compared to Christ and regarded as a great hero in much of the north.
He was the darling of New England high society. It’s where the funding for his weapons came from. Thomas Wentworth Higginson, Samuel Gridley Howe, Theodore Parker, Franklin Benjamin Sanborn, Gerrit Smith, and George Luther Stearns were very influential people. They were Saudis to his Al Qaeda. It’s not like his attempt to ignite a Haitian style massacre was condemned as being a great crime. It would have been pretty hard for people south of the Mason Dixon Line to miss what their northern neighbors had in store for them.