Fort McHenry in the Civil War

A group of musicians in Civil War uniforms in the star fort with a group of Civil War living historians in the background.
Living historians interpreting the Civil War period of Fort McHenry.

NPS/Tim Ervin

In the years following the Battle of Baltimore, Fort McHenry remained an active military fort. The fort went through many upgrades such as building additions, improved bomb proofs, creation of an outer battery, and the installation of larger seacoast Columbiad guns. Following Abraham Lincoln’s election in 1860, Southern slave-owning states began to secede from the United States of America starting with South Carolina. In no place was there a greater rise in tensions than the state of Maryland. Because of Maryland’s role as a border state, Fort McHenry would once again serve an important purpose in a time of war.

A painting depicting the fort during the Civil War. There are several buildings around the fort and lines of union soldiers.
Several units came through Fort McHenry during the war, many used it as a transition period between initial training and seeing the front lines of battle.


Rising Tensions and a Firm Response

In April of 1861 southern batteries opened fire on U.S. troops at Fort Sumter and in response President Lincoln called for 75,000 volunteers to help put down the rebellion. The call for troops also incensed Maryland secessionists and tensions rose in Baltimore as the city became a powder keg ready to explode. The crisis came to ahead when on April 19, 1861 the 6th Massachusetts regiment marched through the city from the President Street Rail Station to the Camden Station to travel to Washington D.C. The sight of federal troops marching through the city angered secessionists who began attacking the troops starting a riot in which 4 soldiers and 12 civilians were killed, and 36 soldiers and hundreds of civilians were wounded.

The outbreak of violence meant federal instillations around Baltimore had an even more important role: use whatever force necessary to keep Maryland in the Union. In July of 1861 General John A. Dix took command of the newly formed Middle Department of the United States Military. Dix set up his command at Fort McHenry and immediately went to work to get the secessionist town to comply with federal rule. Dix invited several prominent Baltimore women who had known southern sympathies to be entertained at Fort McHenry. During the event Dix took the women up to bastion 1 of the fort and directed their attention to the large Columbiad cannon there which was pointed in the direction of Monument Square in the city. Dix informed his guests “if there should be another uprising in Baltimore, I shall be compelled to try to put it down; and that gun is the first that I shall fire.” And so, Fort McHenry would continue to operate for the entirety of the Civil War, with cannon pointed to protect the entrance of the harbor, but also pointed at the center of the city it was charged to protect.

A sketch showing multiple Civil War soldiers standing in front of a building that is labeled "Deserters"
Cincinnati illustrator Thee Jones made a drawing of scenes of life at Fort McHenry in July 1864 during the Civil War.


The American Bastille

Fort McHenry was never attacked during the Civil War, and any further uprisings after the Pratt Street Riots were deterred. The fort’s most important role became what no one could have predicted: that of a prison. The fort’s first major influx of prisoners of war came in the aftermath of the Battle of Antietam (1862), fought in the western part of Maryland. Fort McHenry soon became a much-needed space to house captured Confederate soldiers who were eventually transferred to larger facilities. Fort McHenry’s new role as a transition site for POWs was established and just about any Confederate POWs captured in the eastern theater of war would pass through the site at some point. The largest surge of captured Confederates came following the Battle of Gettysburg (1863) in which 6,957 prisoners were held at the fort at one time.

Fort McHenry’s prison population did not only include Confederate soldiers, however. Following the Pratt Street Riots in 1861, Lincoln recognized the rising tensions in Maryland were too dangerous for the survival of the country if they were able to secede. Drastic measures were taken, and Lincoln suspended the writ of habeas corpus in the state, in doing so he opened the door for private citizens to be arrested and held without trial for showing any sort of Confederate sympathies or other traitorous actions. A political massacre occurred in September of 1861 when a third of the Maryland Delegation was arrested to prevent them from voting on secession, and they were held in Fort McHenry. Other Political prisoners included the mayor of Baltimore, the Baltimore police chief, and a newspaper editor by the name of Frank Key Howard (grandson of Francis Scott Key). These political prisoners at the fort prompted a Supreme Court brief to be issued by Chief Justice Roger B. Taney. The Exparte Merryman brief stated that the President of the United States does not have the right to suspend the writ of habeas corpus, and that power instead was held by Congress. Congress would pass the suspension for Maryland in 1862, meaning even more political prisoners could be arrested and held at Fort McHenry until the end of the war in 1865. For its role in imprisoning political prisoners, Fort McHenry was nicknamed “The American Bastille.”

Last updated: December 11, 2020

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