These ships were all originally USN and USCG WWII Edsall class frigates/cutters converted in the early 1950s to radar picket ships, filling in holes in NORAD’s early-warning system. The scheme had a relatively short life as land-based radars advanced in ability, and Soviet nuclear strategy shifted away from manned bombers to missiles. The ships were retained throughout the 1960s anyways as they were extremely fuel-efficient and cheap to man and operate. Several were used during the Vietnam War in operations “Market Time” and “Sea Dragon“, the interdiction of North Vietnamese jinks and smuggling boats.
The conversions were done out of order with USS Savage being the first.
USS Roy O. Hale was involved in a peculiar situation in 1959. It was noticed that five disruptions along a trans-Atlantic phone cable seemed to coincide with the fishing route of a Soviet trawler. The USN ordered Hale to stop and board the trawler, and seize her if necessary. After boarding the trawler, Hale’s crew discovered no eavesdropping or military equipment and released the ship. Despite the fact that the action was at best outrageous and quite possibly an act of war under maritime law, the incident was quickly forgotten. It seems the trawler’s course was simply a coincidence.
In 1982, the ex-USS Savage was used as one of the first maritime targets for the AGM-88 HARM during a SINKEX.
Tran Khan Du was in refit at Saigon Dockyards when the North Vietnamese army overran South Vietnam in 1975. The ship was on a loaner basis to the South Vietnamese navy and thus still technically American property however Vietnam obviously had no intention of relinquishing her and on 25 September 1975 she was quietly listed as “transferred to Vietnam” in USN records. The Vietnamese refitted her with two SA-N-5 “Grail” MANPADSs . Since 1994 she has been used as a training vessel with the SAM positions deleted.

Original Author: Jason W. Henson