H.L. Hunley was the first submarine to sink an enemy warship in combat. It was built in spring 1862 in Mobile, Alabama at the Park & Lyons Machine Shop by a coalition of machinists and businessmen including engineers James McClintock and Baxter Watson, lawyer Horace L. Hunley, and four members of an organization of underwater "torpedo" (contact-mine) manufacturers called the Singer Submarine Corps. Eight crewmen operated the submersible. Seven individuals sat side-by-side on a wooden bench affixed along the port side of the vessel and turned a hand-cranked propeller featuring an innovative reduction gear system, while the commander was responsible for steering the submarine and deploying the weapons system. Following successful testing in Mobile, the submarine was shipped to Charleston, South Carolina by flatcar in August 1863 at the request of Charleston's military commander General P.G.T. Beauregard. Beauregard hoped the submarine could help break the naval blockade that was then preventing access to the city's harbor.