Baltimore secessionist rioters attack the federal 6th Massachusetts Infantry as it passes through the city to join the defense of Washington. It is the first significant bloodshed and loss of life of the Civil War, as there are fatalities on both sides. A day before, the Black servant of a Pennsylvania officer is hit and injured by a brick.
New President Abraham Lincoln is faced with a hostile city blocking his lifeline from the U.S. Capital to the northern states. He arrests local rebel leaders and soon sends in federal troops to place Baltimore under martial law. The riot becomes a rallying cry that aids recruitment of volunteer troops for both sides.

Maryland soldiers from both North and South fight at the Battle of Front Royal
Soldiers from both North and South units fight at the Battle of Front Royal. in 1861, pictured. A year later they engage again at Gettysburg. These are the only times in US military history that regiments with the same designations from the same state engage in combat.