The Alton Military Prison

key and padlock
A key and padlock from the Illinois State Penitentiary in Alton, Illinois. The Union repurposed the facility as a military prison during the Civil War. The jail key is 3.75″ long. The padlock has a flat metal bar that swings down to cover the key hole. MCHS objects 1938-068-0002 (key) and 1938-068-0001 (padlock).

The state’s first penitentiary

In 1833, Illinois built its very first state penitentiary in Alton, Madison County. The prison was bounded by Fourth, Williams, Second (aka Short), and Mill Streets.

drawing of Alton Prison
Drawing of the Alton Prison that appeared in the St. Louis Post-Dispatch on Sunday, June 15, 1902, with the caption: “Alton Prison as it appeared during the Civil War, drawn for the Sunday Post-Dispatch from memory and old pictures by Thomas Long, of Alton.”

A 25-foot stone wall surrounded the prison grounds, a square area measuring 100 yards on each side. A narrow walkway along the top of the wall connected guard houses. Inside the perimeter, inmates made agricultural tools in short workshop buildings. The warden’s office and house occupied the southwest corner of the grounds. A three-level cell block building with an iron stairway at the south end extended behind the warden’s office.

Improperly planned drainage for construction on the riverfront bluffs caused flooding and recurring sanitation issues. The cells had poor ventilation and inadequate heating. In 1847, prison reformer Dorothea Dix appeared before the Illinois legislature and advocated for closing the prison. The facility was finally shut down in June of 1860.

A Civil War military prison

chest of drawers
Miniature chest of drawers (8″ high x 8.25″ wide x 6″ deep) made by a Southern prisoner-of-war in the Alton military prison during the Civil War. MCHS object 1965-077-0002.

The prison reopened in 1862, when Governor Yates granted General Henry W. Halleck permission to use it as a military prison. The first prisoners arrived on February 9, 1862. In addition to Confederate soldier prisoners-of-war, Union deserters and Southern sympathizers/Copperheads (including some women) numbered among the inmates.

Typical prison activities included making jewelry, playing cards, and walking around the yard. Prisoners washed their own clothes. Those inmates who were sentenced to hard labor spent their time breaking rock within the prison grounds or in a nearby quarry. Some prisoners had to wear a ball and chain. Many attempted escape by tunneling, hiding in coffins, or bribing guards. Infractions were punished by being “bucked and gagged,” being hung by the thumbs, or wearing a barrel.

The Alton Military Prison provided for chaplain services and permitted prisoners to correspond with their friends and families. After Major Morgan took command in October of 1864, prisoners were allowed to receive gifts and provisions. Some prisoners even enjoyed parole privileges in town. But by 1864, overcrowding created unsanitary conditions and food shortages.

“Thirty-two of us occupy a room eighteen feet square; some have bunks, others take the floor. … [I]t is almost impossible to sleep on account of the rats, which run over us all through the night…”

(Griffin Frost, Camp and Prison Journal, entries for January 30-31, 1864.)

Official reports kept for 36 months on the overall prisoner population indicate that 11,764 Confederate POWs passed though the prison. On average, 1,261 inmates lived in the prison each month. But at times new prisoners were admitted before others were transferred or exchanged, creating temporary periods of high congestion in the facility.

A breeding ground for smallpox

painting of Sunflower Island
“Sunflower Island” by Michael B. Mossman, in 2005-2015 Alton Area Paintings. The artist’s caption reads: “During the Civil War Confederate prisoners were housed at the Federal Prison in Alton, Illinois. It is estimated that over a total of eleven thousand Confederate prisoners were kept in the prison during the three year period it was open. Smallpox broke out and many prisoners were isolated on an island in the Mississippi River. The island was known as ‘Sunflower Island.’ It was on Sunflower Island where many Confederate prisoners suffered and died. The prisoners who were not buried at the Confederate Cemetery were buried on the island. Today, the island is covered over by water of the Mississippi River. This painting is a surreal painting and intended to show the prisoners eyes in the sunflowers. It was done in acrylic on an 18 by 24 canvas. Painted in 2014.” Mossman is a former resident of Edwardsville, Illinois, who grew up in Alton.

Smallpox (also known as variola) broke out in the prison in 1862. The epidemic peaked in the winter of 1863-1864.

Smallpox victims developed flat, red sores on their face and extremities. The sores filled with pus. Scabs formed over the lesions and fell off after about three weeks. Contracted by contact with an infected person’s bodily fluids, the virus spread easily in the close prison conditions.

At the height of the epidemic, infected inmates were quarantined on Sunflower Island, a small island in the Mississippi River located 200 yards upstream from the prison. The island (also known as Tow Head Island, McPike Island, Willow Bug Island, Mosquito Island, or Round Island) soon acquired a new name: Smallpox Island. Healthier victims dug mass graves for the bodies of the dead. The island was prone to flooding and began silting away in 1930. It has now completely disappeared.

A monument to the dead

The Alton prison closed at the end of the Civil War. Today only a small portion of the stone wall formerly surrounding the prison grounds remains standing. To the extent that records were kept, the official death count at the prison totaled 1,354 Confederate POWs. These names are listed on the Soldiers Monument in the North Alton Confederate Cemetery on Rozier Street. Approximately 240 documented Confederate soldiers and civilians, and roughly 200 Union soldier inmates, were buried on Smallpox Island.

Alton Military Prison historic site
Photograph of the Alton Military Prison historic site. Modified from a photograph by Nyttend available at

Ideas for Teachers (or anyone who wants to take a deeper dive into the history of the Alton prison)

Some relevant essential questions for students to explore:

  • How do issues of morality influence war?
  • How are people affected by war?

Possible classroom activities:

  • Discuss the moral standards that apply in the treatment of prisoners-of-war.
  • According to the statistics presented above, approximately 10-11% of the Confederate POWs at the Alton Military Prison died during their imprisonment. Compare this survival rate compare to survival rates at other Confederate and Union military prisons. Compare these statistics to survival rates for Civil War soldiers who weren’t imprisoned.
  • Prisoners in the Alton Military Prison made crafts and jewelry. Michael Mossman created a painting of Smallpox Island 150 years after the Civil War. Research other examples of prisoner art and prisoner-inspired art to explore how the experience or contemplation of incarceration affects creativity.
  • Discuss probable effects the Alton Military Prison had on the lives of Altonians.

Sources for this article include newspaper articles from the Alton Telegraph and the following additional sources:

  • “The Alton Penitentiary.” Compiled and written by Madison County Historical Museum staff, C. Longwisch. July 1982. Madison County Historical Society document.
  • Centennial History of Madison County, Illinois and Its People: 1812 to 1912. Edited and compiled by W.T. Norton. Chicago: Lewis Publishing Company, 1912. Available at the Madison County Archival Library.
  • Colegate, Bryan. A Report on the Historical Landscape of the Site of the Alton Penitentiary and Military Prison. Madison County Historical Society document 1994-052.
  • Cox, Jann. Alton Military Penitentiary in the Civil War: Smallpox and Burial on the Alton Harbor Islands. St. Louis District Historic Properties Management Report No. 36. US Army Corps of Engineers: November 1988. Available at the Madison County Archival Library.
  • Frost, Griffin. Camp and Prison Journal. Iowa City: Camp Pope Bookshop, 1994. Available at the Madison County Archival Library.
  • “The Historic Alton Prison.” Brochure. Alton: Greater Alton/Twin Rivers Convention and Visitors Bureau. Madison County Historical Society document.
  • “The Infamous Alton Prison.” Brochure. Alton: Greater Alton Chamber of Commerce. Madison County Historical Society document.
  • Mossman, Michael B. 2005-2015 Alton Area Paintings. [Edwardsville, 2015.] Available at the Madison County Archival Library.