Final answer:
Clement L. Vallandigham was a leader of the Copperheads, the Democratic faction that opposed the Civil War, and became a symbol of the opposition to Lincoln's wartime policies after his 1863 conviction for expressing anti-war sentiments.
Step-by-step explanation:
Clement L. Vallandigham was a prominent figure in American history, known primarily for his political activities during the Civil War era. Vallandigham was a leader of the Copperheads, the faction of the Democratic Party that opposed the Civil War and called for an immediate peace settlement with the Confederacy. His actions and speeches often sparked controversy, especially when he criticized President Abraham Lincoln and the war effort. Vallandigham's most notable brush with the law came in 1863 when he was convicted by a military court for expressing anti-war sentiments and calling for the war's end, which was seen as undermining the Union's military efforts. His conviction was widely criticized by Civil War-era Democrats who saw it as an attack on free speech, and Vallandigham became a symbol of the opposition to Lincoln's wartime policies.