Rock Island Arsenal The Rock Island Arsenal comprises , located on Arsenal Island , originally known as Rock Island , on the Mississippi River between the cities of Davenport , Iowa , and Rock Island , Illinois . It lies within the state of Illinois . The island was originally established as a government site in 1816 , with the building of Fort Armstrong . It is now the largest government - owned weapons manufacturing arsenal in the United States . It has been an active manufacturer of military equipment and ordnance since the 1880s . In 1919 - 20 100 of the Anglo - American or Liberty Mark VIII tanks were manufactured , although too late for World War I . It is designated as a National Historic Landmark . Established as both an arsenal and a center for the manufacture of leather accoutrements and field gear , today it provides manufacturing , logistics , and base support services for the Armed Forces . The Arsenal is the only active U . S . Army foundry , and manufactures ordnance and equipment , including artillery , gun mount s , recoil mechanisms , small arms , aircraft weapons sub - systems , grenade launcher s , weapons simulators , and a host of associated components . Some of the Arsenal ' s most successful products include the M198 and M119 towed howitzer s , and the M1A1 gun mount . About 250 military personnel and 6 , 000 civilians work there . The 2000 census population was 145 . During the Civil War , Arsenal Island was home to a large Union army prison camp for captured Confederate soldiers ( the Rock Island Prison Barracks ) . The island facilities were converted and built in 1863 and was not yet completed in December of that year when the first Confederate prisoners were incarcerated . The construction was makeshift and was built with little notice of prisoners arriving . The first to arrive were 468 Confederate prisoners captured in battles at Chattanooga , Tennessee , although , over 5 , 000 total would swell the population of Rock Island Prison in that month alone . A total of 41 Confederate prisoners successfully escaped during the prison ’ s existence while many more would try but fail . A total of 1 , 964 Confederate prisoners and 125 Union guards are buried in the adjacent military cemetery , including 49 members of the 108th Regiment of United States Colored Troops , most of which died from disease or exposure . The prison camp was operational from December 1863 until July 1865 when the last prisoners were freed . After the war the prison facility was completely destroyed . During its two years in operation , the prison camp housed over 12 , 400 Confederates . Following the war , the government retained ownership of Arsenal Island and used it for various functions . See also : Prisoner camps of the Civil War Other historical sites in the area include the Confederate Cemetery , the Rock Island National Cemetery , 19th century stone workshops , officers ' quarters along the river , Col . Davenport ' s House , and the site of the first bridge built across the Mississippi . Rock Island Arsenal Museum . The Rock Island Arsenal Museum was established on July 4 , 1905 . It is the second - oldest US Army Museum in the US after the West Point Museum . The museum has been closed twice , during World War I and World War II , to provide more space for manufacturing facilities . Exhibits focus on the history of Rock Island Arsenal and Arsenal Island ' s use as a Union prison camp during the American Civil War and its role as a military industrial facility . The museum also contains the second largest collection of small arms weapons in the U . S . Army , and an outdoor vehicle display . Indoor exhibits include ( as of June 2012 ) : Outdoor exhibits include ( as of June 2012 ) :