over the nickname by 1875. Cincinnati also is known as the "City of Seven Hills". The hills form a crescent from the east bank of the Ohio River to the west bank: Mount Adams, Walnut Hills, Mount Auburn, Vine Street Hill, College Hill, Fairmount, and Mount Harrison. Civil War During the American Civil War, many people in the area were "Southern sympathizers" due to Cincinnati's commerce with slave states and history of settlement by southerners from eastern states. Of the people who served in the military, most enlisted with the Union Army, but a large number who served for the Confederates. Some residents participated in the Copperhead movement in Ohio. Cincinnati played a key role as a major source of supplies and troops for the Union Army; It also provided housing for soldiers and their families, both of which were good for the city's economy. The United States Christian Commission, United States Sanitary Commission, and other charities came to the area to assist soldiers and their families. It served as the headquarters for much of the war for the Department of the Ohio, which was charged with the defense of the region, as well as directing the army's offensive into Kentucky and Tennessee. In July 1863, the Union Army instituted martial law in Cincinnati due to the imminent danger posed by the Confederate Morgan's Raiders. Bringing the war to the North, they attacked several outlying villages, such as Cheviot and Montgomery. During the American Civil War, an eight-mile line of defense was built by Cincinnatians along the Ohio River to protect the city. One of the batteries, Battery Hooper, became the site of the James A. Ramage Civil War Museum in Fort Wright, Kentucky. Due to the efforts of the Black Brigade of Cincinnati and the Defense of Cincinnati, forces established to defend Cincinnati did not need to fire a shot during the Civil War. Post Civil War and late 19th century history With nearly 300,000 people, it was the state's largest city, and it was the country's densest population with an average of 37,143 people per square mile. The city had an art academy, art museum, Music Hall, opera house, Exposition Building, and a public library. There were about 130 magazines and newspapers produced in the city. There were more than 200 churches, five hospitals, and college education attainable through University of Cincinnati. In 1888, Cincinnati German Protestants community