Date of Action: 18 April 1945
USCG Units Involved: USS Knoxville; the flagship of the hunter killer group
Sinking/Capture/Assist? Sinking; Coast Guard-commanded hunter-killer group.
Location: 42.22N x 69.46W
Credit by U.S. Navy? Credit was given to USS Gustafson (US Navy warship), Gustafson was part of the hunter-killer group commanded by a Coast Guard officer, CDR Ralph R. Curry, USCG, aboard flagship USS Knoxville.
Enemy Warship's Commanding Officer: Kapitänleutnant Rudolf Premauer
Enemy Casualties: 59 killed in action; all hands lost
USCG Casualties: None
Misc: Sinking credit is questionable--see details below.
U-857, a Type IX C/40 U-boat, departed on a patrol to the waters off Cape Hatteras, North Carolina, on 6 February 1945. She reached the Gulf of Maine in March and apparently began searching for Allied targets. A torpedo attack that damaged the tanker SS Atlantic States just north of Cape Cod on 5 April 1945 alerted the US Navy that a U-boat was operating in American waters (the attack was later attributed to U-857). Units of Escort Division 30, under the command of CDR Ralph R. Curry, USCG, had been undergoing refresher training at Casco Bay when these Allied warships were ordered to form a "hunter-killer" group to search for the U-boat that made the attack on the tanker.
The hunter-killer group consisted of the Coast Guard-manned frigate USS Knoxville, from which Curry flew his pennant, along with another Coast Guard-manned frigate, Eugene, and two destroyer escorts, Gustafson and Micka. Gustafson located a sonar contact in the waters northeast of Cape Cod in the early morning of 7 April. She attacked the target with hedgehogs but these failed to produce an explosion. She then attacked again and this time at least one charge was heard to explode on contact with a submerged object. Gustafson then launched four more hedgehog attacks without achieving any further explosions. Once daylight arrived, Gustafson's crew sighted a large oil slick.
After the war the Navy reviewed captured German records and compared them with the reports of attacks conducted by Allied warships on possible German submarine contacts. U-857 was reported missing by the German U-boat Command in April in the area of the attack by Gustafson. The Navy then gave credit for the sinking of U-857 to Gustafson. [This sinking credit was included on this list because the Gustafson was part of a task force that was commanded by a Coast Guard officer.]
The Foreign Documents Section of the Naval Historical Branch of the U.K. Ministry of Defense revoked this credit in April 1994, surmising that Gustafson's attack was "very probably directed against a nonsub target." Axel Niestlé, in his German U-boat Losses During World War II: Details of Destruction (Annapolis: Naval Institute Press, 1998) claims that "There is presently no known explanation for [U-857's] loss." (Both citations are from Niestlé's U-boat Losses, page 238, note 145.)