Short answers, pulled from the story.
The Baltimore riot of 1861 erupted due to deep divisions between pro-Southern sympathizers and Union supporters within the city. Anti-war mobs blocked the route of the 6th Massachusetts Militia with bricks and paving stones, leading to armed clashes that resulted in multiple deaths.
Five soldiers died or were mortally wounded including Corporal Sumner Henry Needham and privates Luther C. Ladd, Charles Taylor, Addison Whitney, and Sergeant John Ames. At least twelve civilians also lost their lives while many more remained uncounted among the injured.
Major General Benjamin Butler sent Union troops into Baltimore and declared martial law on the 13th of May 1861. He subsequently had the mayor police chief entire Board of Police and city council imprisoned without charges.
Abraham Lincoln suspended habeas corpus to detain political opponents and suppress rebellion after Chief Justice Roger B. Taney ruled the action unconstitutional on the 4th of June 1861. Federal authorities detained twenty-seven state legislators on the 17th of September 1861 using these suspension powers granted under martial law conditions.
Maryland My Maryland became the official state song of Maryland seventy-eight years later in 1939 after James Ryder Randall wrote it following the riots. Officials removed it from being official state song in 2021 following renewed debates about its Confederate origins.