Marching about fifty yards behind the leading Union brigade, Dana's command began to receive artillery fire but continued to head forward. Shortly after entering the West Woods, Dana's brigade was struck hard on their left by Confederate troops, and became in danger of being completely surrounded and cut off. Maneuvering his soldiers in the difficult terrain and spacing, Dana led his men to the relative safety of the Miller Farm, despite receiving a serious wound to his left leg. When the pain in his leg became unbearable, Dana turned command of his brigade over to his senior regimental commander, Col. Norman Hall, and was carried to a Union field hospital in nearby Keedysville for treatment. After spending two days at the field hospital, Dana was sent to Washington, D.C. and later again to Philadelphia to recover. At Antietam, Dana's command lost about 900 men killed, wounded, or missing.