From the NPS website: The defining events of Fort Pulaski occurred during the American Civil War. In April of 1862, Union troops directed rifled cannon fire at the fort breaching the southeast angle. The quick success of this experimental cannon surprised military strategists. The accuracy and range of the rifled cannon rendered brick fortifications obsolete. Immediately after capturing the fort, Union Major General David Hunter, an ardent abolitionist, ordered the release of area slaves. Many were recruited into the Union army comprising the First South Carolina Colored Regiment.