Indiana, a state in the Midwestern United States, played an important role during the American Civil War. Despite significant anti-war activity in the state and southern Indiana's ancestral ties to the Southern United States, it was a mainstay of the Union war effort, and hunted down disloyal elements. During the course of the war, Indiana contributed approximately 210,000 soldiers and millions of dollars of horses, food and supplies to the U.S. Army. Residents of Indiana, also known as Hoosiers, served in every major engagement of the war and almost every engagement—minor or otherwise—in the western theater of the war. Indiana, an agriculturally rich state containing the fifth-highest population in the Union and sixth-highest of all states, was critical to Northern success.