Humanities › History & Culture Rock Island Prison Union Prison During the American Civil War Share Flipboard Email Print Historic Map Works LLC / Getty Images History & Culture Military History Civil War Battles & Wars Key Figures Arms & Weapons Naval Battles & Warships Aerial Battles & Aircraft French Revolution Vietnam War World War I World War II American History African American History African History Ancient History and Culture Asian History European History Genealogy Inventions Latin American History Medieval & Renaissance History The 20th Century Women's History View More By Martin Kelly History Expert M.A., History, University of Florida B.A., History, University of Florida Martin Kelly, M.A., is a history teacher and curriculum developer. He is the author of "The Everything American Presidents Book" and "Colonial Life: Government." our editorial process Martin Kelly Updated May 13, 2019 In August 1863, United States Army began construction of the Rock Island Prison. Located on an Island between Davenport, Iowa and Rock Island, Illinois, the prison was designed to house captured Confederate Army soldiers. The plan was to build 84 barracks with each one housing 120 prisoners along with their own kitchen. The stockade fence was 12 feet high. There was a sentry placed every one hundred feet with only two openings to get inside. The prison was to be built on 12 acres of the 946 acres that encompassed the island. The First Prisoners In December 1863, the yet unfinished Rock Island Prison received its first prisoners who had been captured by General Ulysses S. Grant troops during the Battle of Lookout Mountain, in Chattanooga, Tennessee. While the first group numbered 468, by the end of the month the prison population would exceed 5000 captured Confederate soldiers, some of them also having been captured at the Battle of Missionary Ridge, Tennessee. Temperatures were below zero degrees Fahrenheit in December 1963 when those first prisoners arrived. The temperature would be reported as low as thirty-two degrees below zero at times during for the rest of that first winter. Disease and Malnutrition at Rock Island Since the construction of the prison was not completed when the first Confederate prisoner’s arrived, sanitation and disease, especially a smallpox outbreak, were issues at that time. As a response, in the spring of 1864, the Union Army built a hospital and installed a sewer system which helped improve conditions inside the prison walls immediately, as well as ending the smallpox epidemic. In June 1864, Rock Island Prison severely changed the amount of rations that prisoners received due to how Andersonville Prison was treating Union Army soldiers who were prisoners. This change in rations resulted in both malnutrition and scurvy which led to the death of Confederate prisoners at the Rock Island Prison facility. During the time that Rock Island was in operation, it housed over 12,000 Confederate soldiers of which nearly 2000 died, but although many claim that Rock Island was comparable to the Confederate’s Andersonville Prison from an inhumane standpoint only seventeen percent of their prisoners died compared to twenty-seven percent of Andersonville’s total population. In addition, Rock Island had enclosed barracks versus the man-made tents or totally being in the elements as was the case in Andersonville. Prison Escapes A total of forty-one prisoners escaped and were not recaptured. One of the largest escapes occurred in June 1864 when several prisoners tunneled their way out. The last two were caught as they came out of the tunnel and another three were caught while still on the island. One escapee drowned while swimming across the Mississippi River, but another six successfully made it across. Within a couple of days, four of those were re-captured by Union forces but two were able to completely elude capture. Rock Island Closes The Rock Island Prison closed in July 1865 and the prison was totally destroyed shortly thereafter. In 1862, the United States Congress established an arsenal on Rock Island and today it is our country’s largest government operated arsenal that encompasses almost the entire island. It is now called Arsenal Island. The only remaining evidence that there was a prison that held Confederate soldiers during the Civil War is the Confederate Cemetery where approximately 1950 prisoners are buried. Additionally, the Rock Island National Cemetery is also located on the island, where the remains of at least 150 Union guards are interred, as well as over 18,000 Union soldiers.