The merchant schooner Rhoda H. Shannon, which departed Boston on March 26 with a shipment of ice bound for Savannah, took a precipitous wrong turn the afternoon of April 3, a mistake its captain accredited to faulty navigational equipment. To make matters even worse, the ship arrived in the “midst of a gale that had been blowing for several days,” leaving the harbor’s waters “white with foam.” According to the ship’s captain, he mistook the channel into Charleston Harbor as the entrance to Tybee Island, which lay at the mouth of the Savannah River. He then raised the U.S. flag per protocol for a ship requesting a local pilot come aboard to bring the schooner in safely. When no one responded to his signal, he decided to pilot the ship into the harbor himself.
Lt. Col. W. G. DeSaussure, commander of the Confederate batteries on Morris Island, was under orders to prevent any ship flying the U.S. flag from entering the harbor. As Rhoda H. Shannon passed by the island, his troops fired several warning shots across the schooner’s bow. The Shannon dropped anchor. DeSaussure sent a skiff out to assess any damage to the schooner or her crew. From Fort Sumter, an alarmed U.S. Maj. Robert Anderson did the same.
The ship’s master explained his mistake to the Federal and Confederate representatives, both of whom accepted his story and expressed relief that no one had been injured nor the schooner damaged. DeSaussure promised Shannon’s master that it could lie at anchor outside the harbor’s bar without further trouble until the foul weather had passed. Soon afterward, the Shannon headed out to sea. DeSaussure reassured Charlestonians that the incident had not been another attempt to supply Fort Sumter, but simply a merchant ship that had lost its bearings. Crisis averted. While all of this was going on, the state of South Carolina ratified the Confederate Constitution by a vote of 114 to 16 – and Lincoln began to embark on a plan that would change history. Check back in tomorrow.
Sources

Keller, Rudi. “150 Years Ago: Tensions Rise as Fort Sumter standoff continues,” Columbia Daily Tribune, April 3, 2011.

“The Rhoda H Shannon Incident.” American Civil War High Command

“Civil War Naval History,” History Central