The destroyer USS Ward (DD 139/APD 16) is famous for being the first American ship to sink a Japanese vessel, a mini-sub, just hours before the main attack on Pearl Harbor. But less famous is the first American ship to sink a Nazi U-boat. That impact of that ship's kill, incidentally, would reverberate over six decades later.
That vessel was USS Roper (DD 147), a Wickes-class destroyer. Wickes-class destroyers were built during World War I and carried four four-inch guns, a single three-inch gun, and a dozen 21-inch torpedo tubes. These vessels were feeling their age as World War II bubbled up on the horizon but were pressed into service to hold the line until newer vessels came into the fleet.
According to the Dictionary of American Naval Fighting Ships, the Roper had taken part in a variety of deployments in the peacetime Navy between World Wars. The vessel had been off Cape Cod when Pearl Harbor was attacked. After a quick refit, she was escorting convoys. Then came the fateful encounter.
U-Boat.net reports that on April 14, 1942, the Roper detected U-85 on the surface, about 20 miles from Cape Hatteras, North Carolina, two weeks after rescuing 70 survivors from a sunken merchant ship. First, the destroyer opened fire, scoring a number of hits. As the fatally stricken U-boat slipped beneath the surface, the destroyer unleashed a salvo of depth charges to ensure a kill. None of U-85's crew survived.
Almost six decades after the kill, the U-85's wreck was looted and private divers made off with an Enigma machine. In the wake of that incident, Congress passed the Sunken Military Craft Act, which provides tough penalties for looting submerged war graves.
After that kill, the Roper still served, doing a number of convoy runs. Then, she was converted to a destroyer transport and re-designated APD 20. In 1945, she was damaged by a kamikaze. Repairs were still underway when Japan surrendered. She was sold for scrap in 1946.