The outbreak of the Civil War in April 1861 immediately affected the Baltimore Steam Packet Company. On April 19, two days after Virginia's secession, a violently pro-Southern mob in Baltimore attacked Union soldiers en route to Washington, D.C. as the troops marched through the city's streets between railroad stations. Thereafter known as the Baltimore riot of 1861, the resulting loss of life and local unrest also threatened the , a U.S. Navy ship in Baltimore at the time. Later that same day, the Baltimore Steam Packet Company declined to transport Union forces from Baltimore to the beleaguered Union naval yard facility at Portsmouth, Virginia.