Answer:
Abraham Lincoln was an important figure in the American Civil War because he was the president of the United States at the time and was ultimately responsible for the Union's victory in the war. He issued the Emancipation Proclamation which declared all slaves in the Confederacy to be free and he also gave the famous Gettysburg Address.
Jefferson Davis was an important figure in the American Civil War because he was the president of the Confederacy and the leader of the Confederate government during the war. He was responsible for managing the Confederate army and resources and ultimately led them to their defeat. He was seen as a hero to many Southerners and a villain to many Northerners.