In July 1862 Titus took a leave of absence due to poor health and returned to his home in Syracuse. While he was home recovering he was appointed colonel of the new 122nd New York State Volunteer Regiment, by the governor of New York. The 122nd regiment joined the Army of the Potomac in September 1862 at Sharpsburg on the final day of the Battle of Antietam. Three months after Antietam, with Titus in command, the 122nd found themselves supporting the Pennsylvania Reserves in the assault on Fredericksburg Heights. The regiment spent four hours under artillery fire with only four men wounded at the end of the day.