 Anxious about the risk of secessionists capturing Washington, D.C., given that the capital was bordered by Virginia, and preparing for war with the South, the federal government requested armed volunteers to suppress "unlawful combinations" in the South.Soldiers from Pennsylvania and Massachusetts were transported by rail to Baltimore, where they had to disembark, march through the city, and board another train to continue their journey south to Washington.As one Massachusetts regiment was transferred between stations on April 19, a mob of Marylanders sympathizing with the South, or objecting to the use of federal troops against the seceding states, attacked the train cars and blocked the route; some began throwing cobblestones and bricks at the troops, assaulting them with "shouts and stones".