By April 1861 it had become clear that war was inevitable. On April 16 Steuart's son, George H. Steuart, then an officer in the United States Army, resigned his captain's commission to join the Confederacy. On April 19 Baltimore was disrupted by riots, during which Southern sympathizers attacked Union troops passing through the city by rail. Steuart's son commanded one of the Baltimore city militias during the disturbances of April 1861, following which Federal troops occupied the city. In a letter to his father, the younger Steuart wrote: