Union

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 purported secession of the 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.

Many Americans in the 19th century commonly used the term "the Union" to mean either the federal government of the United States or the unity of the states within the federal constitutional framework. The Union can also refer to the people or territory of the states that remained loyal to the national government during the war. The loyal states located mostly north of the Mason–Dixon line were also known as the "North", although four southern border states and West Virginia, when it became a state during the war, remained loyal to the Union, and many Black Southerners (both free and enslaved) and Southern Unionists opposed secession and supported the Union war effort.