The Cape Henry Lighthouse has guided mariners entering and navigating the Chesapeake Bay since 1792. Because the mouth of the Chesapeake Bay has many dangerous shoals and is the site of numerous shipwrecks, the light served as an important aid to navigation. The tower light was extinguished twice between 1792 and 1881, during the War of 1812 to throw the British fleet off course and during the American Civil War as a deterrent to the Union fleet blockading southern ports. The tower originally contained a whale oil lantern, which was replaced several times as technology improved, and the final lantern was a second-order Fresnel lens that could project stationary light 15 miles out to sea. In the 1850s, a fog bell was added to warn mariners, and the lighthouse's distinct visual characteristics, including its light pattern and exterior design, were noted on navigational charts.
