Lincoln wanted to prevent Maryland from seceding because what would happen?
Washington, D.C. is our nation’s capital. It was created when Maryland and Virginia donated land as part of the compromise to deal with our nation’s debt. Since Maryland and Virginia were considered part of the South, there could be issues if the country ever split along regional lines.
When Virginia decided to secede from the Union, President Lincoln knew there could be an issue with our capital. Since Maryland had slaves, there was a very good possibility that Maryland could secede from the Union. If Maryland seceded from the Union, our capital would be cut off from the Union. It would have been located in the Confederacy. As a result, President Lincoln had to be sure Maryland stayed in the Union.
To prevent the Maryland legislature from voting to secede, President Lincoln ordered the arrest of those legislators that supported secession. This prevented Maryland from seceding. By keeping Maryland in the Union as a border state, our capital wouldn’t be cut off from the Union.