Sumter raised a local militia group in Stateburg. In February 1776, Sumter was elected lieutenant colonel of the Second Regiment of the South Carolina Line of which he was later appointed colonel. in 1780 he was appointed brigadier general, a post he held until the end of the war. He participated in several battles in the early months of the war, including the campaign to prevent an invasion of Georgia. Perhaps his greatest military achievement was his partisan campaigning, which contributed to Lord Cornwallis' decision to abandon the Carolinas for Virginia.