Transported south by rail and then marched to the vicinity of Falmouth, Virginia in early January 1863, and then assigned to operations along the Rappahannock River, Rohm was transferred from Company F to the central command of the 16th Pennsylvania Cavalry, and promoted to the rank of chief bugler on February 1, 1863, Engaged with his regiment in Union cavalry operations at the Rappahannock Bridge and Grove Church (February 5–7) and Hartwood Church (February 25), Rohm then helped to call and direct his fellow 16th Pennsylvania Cavalrymen in combat in the Battle of Kelly's Ford (March 17); operations near Bealeton Station (April 13–27) and Elk Run (April 13); the Chancellorsville Campaign (April 26 – May 8), including Stoneman’s 1863 Raid (April 13 – May 10) and actions at Kelly's Ford (April 29) and Ely's Ford (May 2); the Gettysburg Campaign (June 3 – July 24), including the battles of Brandy Station (June 9), Aldie (June 17), Middleburg (June 18–19), and Gettysburg (July 1– 3), as well as operations at Steven’s Furnace (July 5) and Shepherdstown, West Virginia (July 14–16); the Union's advance to the Rapidan (September 13–17), which included the Battle of Culpeper Court House (September 13); the Bristoe Campaign (October 9–22), which included the First Battle of Auburn (October 13) and the Battle of Bristoe Station (October 14); and the Mine Run Campaign (November 26 – December 2).