American Civil War: Union forces enter Atlanta as the city surrenders, ending the Atlanta campaign as a victory for General William T. Sherman.

The Union is a term used to refer to the federal government and loyal states of the United States during the American Civil War. Its military forces and civilian population resisted the secession of the Southern slave states that formed the Confederate States of America following the 1860 election of Abraham Lincoln as president of the United States. Lincoln's administration asserted the permanency of the federal government and the continuity of the United States Constitution, and it refused to recognize the Confederate government.