Complex sentence: CSS "David" was one of the South's secret weapons, similar to the submarine "H.L. Hunley", the boat was designed to destroy enemy ships by stealthily sneaking up to their sides and placing an explosive on their hulls.
Split into simpler sentences: CSS "David" was one of the South's secret weapons. Similar to the submarine "H.L. Hunley", the boat was designed to destroy enemy ships by stealthily sneaking up to their sides and placing an explosive on their hulls.