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Allied Minesweeping Operations during Operation Avalanche

June 29, 2017 | By Marcus Thompson, Naval History & Heritage Command Intern (Dartmouth College)
Minesweeping operations are an often overlooked chapter of Operation Avalanche, the 1943 invasion of Salerno. Minefields in the Gulf of Salerno were first detected by HMS Shakespeare (P221), a British beacon submarine active in the area since August 29, 1943.[1] Using magnetic detection devices, the submarine located a plethora of German "V" and Italian "I", "J", and "K" mines in the gulf, thus setting the stage for an extensive mine countermeasures operation. The threat these mines posed also compelled Allied transports to lower their landing craft nine to twelve miles off beaches on D-Day in order to allow time for minesweeping operations.

In the American Southern sector off the coast of Paestum, the Task Group (TG) 81.8 Minesweeper Group was commanded by Commander Alfred H. Richards, USN. A 1923 U.S. Naval Academy graduate, Richards had served on submarines and on the heavy cruiser Chicago (CA-29) in the late 1930s before transferring to mine warfare in 1942. As executive officer on the fleet minelayer Terror (CM-5), he participated in the 1942 invasion of North Africa and laid a minefield off Casablanca. In March 1943, he assumed command of Mine Squadron 6 with an additional duty as commander Mine Division 16.[2] 

At Salerno, his minesweeping task group was composed of ten small motor minesweepers (AM) and 12 YMS sweepers.[3] At 12:01 a.m. on? Sept. 9, Commander Richards' flotilla of wooden-hulled minesweepers embarked behind four Landing Craft Support (Large) vessels for each beach where allied forces were to land. Minesweepers had a dual mission. First, they were to conduct a single sweep to create channels through the minefields between the line of departure for landing craft (about 6,000 yards offshore) and transport ships before H-hour (3:30 a.m. on Sept. 9). During the second phase of the operation, minesweepers had to clear anchorages and widen approach channels in order for destroyers and cruisers to move closer to the coast for gunfire support. Minesweepers were also tasked with escorting craft in for the assault and patrolling the boundaries of cleared channels. During all of the second phase, TG 81.8 units came under frequent air attack and were in constant danger from wayward mines.[4] With only a few hours to clear channels for landing craft, Commander Richards' mission was far too ambitious for his small force.

While transiting to beaches, troops reported that floating mines hampered efficient approaches to the shore. LST-386, carrying a pontoon causeway, blew up after hitting a mine, causing 43 casualties. A similar fate, although with far fewer casualties, befell the British monitor, HMS Abercrombie (F109) the first surface ship to engage in naval gunfire support (NGFS) during the invasion.[5] Given the immense task of the minesweepers and the paucity of prior intelligence on the minefields, however, it is remarkable that channels were swept well enough for the invasion to succeed with so few casualties attributed to mines.[6] 

Further complications arose when fire control areas had not been cleared for NGFS. Between 3:30 a.m. and roughly 9:00 a.m., troops on beaches were stranded without communications or NGFS. With the assistance of a spotter plane deployed from USS Philadelphia (CL-41) to locate additional mines, Allied minesweepers were able to finish their mission during daylight. Commander Richards' minesweepers worked from the very beginning of D-Day well into the morning to clear fire control areas. At approximately 9:00 a.m., NGFS ships occupied their designated areas and were able to unleash their devastating firepower on German troops, tank concentrations, and artillery.
Photo By: NHHC
VIRIN: 210624-N-ZX259-5184

Allied forces elected to refrain from sweeping all minefields. Select fields were left in place to provide cover for potential German torpedo boat and submarine attacks, and gaps between the fields were patrolled to further guard against such threats. Remembering the torpedo attacks against invading forces in North Africa at Fedhala, Vice Adm. H. Kent Hewitt, USN, the overall naval commander at Salerno, also held a mine-laying group in readiness at Bizerta to lay more cover fields if required.[7] By the conclusion of the entire operation, Allied minesweepers had cleared a total of 275 mines.[8]

Minesweepers were operating on short-term intelligence, commanded by some of the Navy's most junior officers, and given only a few hours to execute a difficult mission. Despite complications including incompletely swept channels for landing craft and delayed NGFS, Adm. Hewitt commended the wooden ships and iron men of the minesweeping force in his action report, acknowledging flawless execution within their capabilities.[9] Additionally, Commander Richards was awarded the Legion of Merit for his successful command of minesweeping forces. He later received a Navy Cross as commander of the Minesweeping Group at Anzio in 1944 and retired as a Rear Admiral.[10]  

[1] Admiral H. Kent Hewitt, USN, The Allied Navies At Salerno: Operation Avalanche - September 1943, (Annapolis: United States Naval Institute, September, 1953), 964.
[2] Rear Admiral Alfred H. Richards, USN, Officer Bio File, NHHC.
[3] Rear Admiral Samuel Eliot Morison USN, History of United States Naval Operations in World War II Volume Nine: Sicily-Salerno-Anzio, January 1943-June 1944, (Boston: Little, Brown & Company, 1954), 253 and 392.
[4] Vice Admiral H. K. Hewitt, USN, The Italian Campaign: Western Naval Task Force, Action Report of The Salerno Landings, September - October, 1943, (United States Eighth Fleet: 11 January, 1945), 255.
[5] Hewitt, 254.
[6] Morison, 274.
[7] Hewitt, The Allied Navies at Salerno, 974-975.
[8] Hewitt, 255.
[9] Hewitt, 254.
[10] Rear Admiral Alfred H. Richards, USN, Officer Bio File, NHHC.