The first Union troops killed in the Civil War were on their way to Washington DC when they were attacked by Maryland civilians defending their lands from invading troops. Known as the Pratt street riot or the Baltimore riot.
The song "Maryland, My Maryland" was published. It was the most anti Lincoln anti North song ever. It later became Maryland's state song. This song refers to Lincoln as a 'Tyrant' and 'Despot' and a 'Vandal'.
The day after "Maryland, My Maryland" was published...
Lincoln suspended the writ of habeas corpus in Maryland.
Lincoln sent the Union Army to occupy Annapolis and Baltimore, and declared martial law. He sent Union troops door to door in these areas to confiscate firearms.
Over the course of the next few months, the Union arrested several thousand Marylanders suspected of Southern sympathies.
Lincoln had arrested 30 members of the Maryland state legislature. A duly elected US Congressman representing Maryland, Henry May was arrested. The mayor of Baltimore and police commissioner of Baltimore were arrested. Most of the Baltimore city council was arrested. These political detainees were imprisoned in Fort McHenry and Point Lookout without trial, in many cases, for several years.
These arrests of Maryland's lawmakers and officials and citizens made many Marylanders upset.
One of them was John Wilkes Booth.
"Sic Semper Tyrannis"