Some border states had a hard time deciding which side to join. Maryland was split between the north and the south.
Maryland had traditionally been considered a southern state, and some people in Maryland wanted slavery to remain legal. Others wanted to remain in the Union, and they pointed to the large presence of Federal soldiers stationed in the capital at Annapolis, Maryland.
About a week after the Battle of Fort Sumter, the people of Maryland began discussing joining the confederacy, but people throughout the state were split on the issue. Fighting began breaking out in the streets between pro-north protesters and pro-south protesters.
On Friday, April 19, 1861 just seven days after the Battle of Fort Sumter, soldiers from New England were traveling through Maryland to answer Lincoln's call for 75,000 more troops.
Pro-southern protesters in Maryland found out that these Union troops were passing through Baltimore and they wanted to stop them from reaching Washington D.C.
The pro-southern protesters began attacking the soldiers from New England. and a riot broke out in the streets of Baltimore.
Four soldiers and twelve civilians were killed in the Baltimore Riot of 1861.
Abraham Lincoln did not want Maryland to join the confederacy. This would cut off Washington D.C. from the Middle and New England states. Lincoln knew that he had to do something to keep Maryland in the Union.
A few days after the riot Abraham Lincoln sent thousands of federal troops to occupy Baltimore. Lincoln had learned that the government officials in Baltimore were going to try to secede so he sent Federal Troops into Maryland to stop them.
Once the Federal Troops arrived, Lincoln declared martial law. He had the Mayor, Police Chief and the entire City Council arrested and imprisoned so they could not vote to secede.
When the Maryland state government attempted to meet at the capitol in Annapolis to discuss what Lincoln had done in Baltimore, the President had them arrested and thrown in jail too, so that they could not vote to secede either.
Even though the state of Maryland had voted to remain neutral, Lincoln and the federal government had decided to take the state by force, securing Maryland as part of the Union, without even firing a shot.