The first shots of the war were fired at nearby Fort Sumter in 1861.
Charleston county sheriff’s spokesman Major Eric Watson said the cannonballs were found at Folly Beach on Sunday afternoon. Bomb squad members could not immediately reach the area because of the rising tide.
Watson said once the sea level dropped, technicians would make the beach safe. He said residents might hear a small boom.
The weakening storm left the US on Sunday but its impact continues to be felt in North Carolina, where floods are forecast over the next few days as rainwaters flow downstream.
Thousands of people found themselves trapped in homes and cars during the torrential rains. Rescue helicopters plucked some of them from rooftops, and military vehicles were used to reach others, including a woman who held on to a tree for three hours after her car was overrun by floodwaters.
The storm killed nearly 900 people in Haiti and at least 18 in the US, nearly half of them in North Carolina. Most were swept away by floodwaters.
US civil war cannonballs unearthed on beach after Hurricane Matthew
11 October 2016
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A bomb squad has been called to a South Carolina beach after Hurricane Matthew apparently unearthed US civil war cannonballs from the sand.
