In service with the US Navy since 1995, Harpers Ferry class is the next evolution of the Whidbey Island class dock landing ship. This design sacrifices landing craft capacity for more cargo space, making it closer to an amphibious transport dock type, but was not designated as such. Externally, the two classes can be distinguished by the positions of weapons: The Harpers Ferry class has the Phalanx CIWS mounted forward, and the RAM launcher on top of the bridge, while the Whidbey Island has the opposite arrangement.A total of four ships were built between 1991 and 1998: Harpers Ferry LSD-49, Carter Hall LSD-50, Oak Hill LSD-51, and Pearl Harbor LSD-52. These are dock landing ships which support amphibious operations including the landing of forces onto hostile shores.