The Confederates had put up a very extensive and complicated field of obstructions to prevent passage of the channels into Charleston Harbor, something that the North greatly wanted to do. Celebrated USS Monitor inventor John Ericsson had come up with another innovation to do just this.
His anti-obstruction torpedo was placed at the bow of the monitor USS Patapsco on this date. The device was a cast iron shell some 23-feet long and 10-inches in diameter containing 600 pounds of powder and was suspended from a raft attached to the ironclad's bow and held in position by two long booms.
The demonstration went favorably and the shock was barely noticed aboard the Patapsco, though a "really fearful" column of water was thrown some 40 to 50 feet into the air. A problem, however, was that he raft really interfered with the Patapsco's maneuverability.