Flag Garrison Flag Major Robert Anderson raised this large garrison flag over the unfinished Fort Sumter in Charleston harbor on December 26, 1860. It was flying on April 12, 1861 when the Confederate forces began firing on the fort. On April 13th, the garrison flag ripped from below the 4th red strip to the hoist. Wool bunting, 19 feet 1 inch by 24 feet 1 inch Fort Sumter National Monument, FOSU 8