When the American Civil War broke out, Mitchel turned soldier. He happened to be in New York when the news of the Battle of Fort Sumter came and, being asked to speak at a public meeting, poured out the deep emotions of his fervid soul in a passionate appeal whose eloquence produced an effect like that of the orations or Demosthenes, Cicero, and Burke. Men and women wept aloud; the cheering drowned his words and the speech he made has been regarded as worthy to be placed alongside abolitionists Abraham Lincoln, Charles Sumner, Wendell Phillips, and Henry Ward Beecher.