What term best describes what President Lincoln meant in his First Inaugural Address Monday March 4th 1861 by saying A disruption of the Federal Union heretofore only menaced?

Answer 1

President Lincoln in his First Inaugural Address Monday March 4th 1861 was referring to Secession when he said, "A disruption of the Federal Union, heretofore only menaced, is now formidably attempted."

Answer 2

See also the text, A Federal Republic: Lincoln’s First Inaugural and the Nature of the Union by Herman Belz

"Lincoln was prepared for the challenge that awaited him, a challenge which, he said in farewell remarks at Springfield, was “greater than that which rested upon Washington.” The Inaugural address marked the formal constitutional beginning of the work of “reinaugurating”[14] the authority of the government of the United States. Seven states had seceded, and four others were poised to join them depending on circumstances. Lincoln’s task was to explain why secession was wrong and preservation of national union right. It was necessary to establish the reason and justice of federal republican union as the theoretical and practical alternative to minority-rule anarchy based on state sovereignty." (bold added)