The strenuous effort failed, and the war started in April 1861.
At first, it looked as if neighboring
Virginia would remain in the Union. When it unexpectedly voted for secession, there was a serious danger that the divided state of
Maryland would do the same, which would totally surround the capital with enemy states. President
Abraham Lincoln’s act in jailing Maryland's pro-slavery leaders without trial saved the capital from that fate.
Faced with an open rebellion that had turned hostile, Lincoln began organizing a military force to protect Washington. The
Confederates desired to occupy Washington and massed to take it. On April 10 forces began to trickle into the city. On April 19, the
Baltimore riot threatened the arrival of further reinforcements.
Andrew Carnegie led the building of a railroad that circumvented Baltimore, allowing soldiers to arrive on April 25, thereby saving the capital.