On April 21 Governor Wise called the Richmond Howitzers into state service and sent them down the James River to stop the "USS Pawnee", allegedly en route to shell Richmond. They were then sent to barracks established at Richmond Baptist College under Col. John B. Magruder, who had fought as an artillery officer in the Mexican War and who requested ten cadets from the Virginia Military Institute as drill instructors. When enlistments proved heavy, the unit expanded into a battalion at the suggestion of Col. Edward Porter Alexander (who would later become CSA General Longstreet's artillery commander). On May 1, 1861, Randolph accepted a commission as major and command of the Richmond Howitzers, with three companies designated (a fourth company was started in July but disbanded in August when recruitment lagged). He sent Lt. John Thomson Brown with several militiamen to Gloucester Point, where on May 7 they fired on the "USS Yankee", thus the first hostile shot fired in that conflict in Virginia. On May 13, the battalion left the college and encamped on the Mechanicsville Turnpike for a while until moving to Chimborazo Hill, where they posted their guns overlooking the James River at Rockett's Landing, where many slaves disembarked. Later in the month, First Company was sent to Manassas Junction (and returned for the battle below, but were then sent to Fairfax Court House where they were involved in a friendly fire incident on July 4, and were not actually called into action at the First Battle of Manassas, only experienced hostile fire); Second Company to Yorktown (where they joined General Magruder's forces on May 27 and did not return, being reassigned) and Third Company to the lower Peninsula, where Randolph became General Magruder's artillery commander and designed fortifications to secure Yorktown and the Hampton Roads area. On June 10 Randolph's Howitzers fought the Battle of Big Bethel near Yorktown, their only engagement as a battalion during the war, and in which three men were wounded. His defenses anticipated Union General George McClellan's campaign of the following spring.