Although the regiment was forced to miss the subsequent Maryland Campaign due to regiment-wide sickness, Kimball's Brigade attacked Confederate positions at the Sunken Road at Antietam and suffered serious losses in a prolonged firefight, earning the nickname "Gibraltar Brigade." They marched to Harpers Ferry after Robert E. Lee's Army of Northern Virginia withdrew from Maryland, staying there until October 30, when the brigade marched towards Falmouth, Virginia. The regiment fought at the disastrous Battle of Fredericksburg in December; among the losses was their wounded Colonel James H. Godman. Then it was part of the infamous January "Mud March," one of Ambrose Burnside's follies as the commanding general of the Army of the Potomac. The 4th Ohio next saw action during the Battle of Chancellorsville under new brigade commander Samuel "Red" Carroll.