The U.S. Navy built only a few warships in the gunboat (PG) category prior to World War II, and (discounting PG-43 through 48, which were river gunboats later redesignated PR) only two were laid down after World War I, the Erie (PG-50) and the Charleston (PG-51). Designed in response to Navy General Board discussions in 1932 on the need for powerful patrol vessels for use in isolated Central American and Asian waters, they were the largest U.S. Navy gunboats and the most powerfully armed, being outfitted with four single 6-inch/ 47-caliber guns and a single Mk 35 director. A platform abaft the funnel carried either boats or a single observation floatplane, and to guard against the growing aerial threat, they were given provision to carry four quadruple 1.1-inch antiaircraft mountings, although initially they carried only four single .50-caliber water- cooled machine guns. At the outset of World War II, the 328.5-foot pair displaced 2,339 tons full load and could achieve 20 knots on their twin steam turbine engines. Range was a generous 8,000 nautical miles at 12 knots. The Coast Guard, impressed with the pair, employed their propulsion plant and underwater hull lines in the seven highly successful Treasury-class cutters.
The Erie, seen shortly after commissioning on 1 July 1936, with an SOC-series floatplane amidships and without 1.1- inch or .50-caliber antiaircraft weapons. Prior to World War II, she spent most of her time alternating with her sister as flagship of the Special Service Squadron, operating from the Canal Zone. Transferred from the Pacific side of the canal to the Atlantic in June 1942, the Erie performed convoy escort duties until September, when she was moved to Trinidad. On 12 November 1942, en route to Guantanamo Bay, she was torpedoed near Curasao; reboarded on 16 November, she was brought into Willemstadt Harbor but capsized in port on 5 December and was not repaired.
The Erie, in a prewar photo, with 1.1- inch antiaircraft guns fitted abreast the tripod foremast, before the bridge, and abaft the tall searchlight tower. Note the canvas awnings rigged aft for tropical service and the awnings furled on poles stretching from the bow to just forward of the bridge.
The Charleston, commissioned on 8 July 1936 and seen here wearing camouflage in March 1944, was dispatched from Central American waters to Seattle in September 1940 to become flagship for the Commander, Alaskan Sector, 13th Naval District, making five cruises to the North Pacific prior to the onset of hostilities with Japan. Her active wartime service was entirely in Alaskan waters, operating from Dutch Harbor or Kodiak. Taking part in the assault on Attu in May 1943, the Charleston bombarded Chichagof Harbor on the 13th and dodged an aerial torpedo attack on 22 May. The ship made a brief cruise to Chinese waters from November 1945 before returning to San Francisco for decommissioning on 10 May 1946; she became the Massachusetts Maritime Academy training ship in 1948. At war’s end, the Charleston displaced 2,546 tons full load and had gained eight single 20- mm antiaircraft guns and two depth charge racks; she retained the 1.1-inch mounts throughout her naval service.