The year of 1863 proved to be an intense one for Anderson and his fellow 1st West Virginia Cavalrymen. Ordered to march for Pennsylvania during the early summer, they participated in the Union Army's tide-turning Gettysburg Campaign, including the battles of Hanover (June 30) and Gettysburg (July 1–3), and then helped to drive Confederate troops from Pennsylvania into Maryland and Virginia, engaging in the battles of Williamsport (July 6–16), Boonsboro (July 8), and Mine Run (November 27–December 2). Two days before Christmas that year, Anderson then re-enlisted with the 1st West Virginia Cavalry at New Creek, West Virginia, earning the designation of "Veteran Volunteer".