DEFENSIVE MINE FIELDS;
HARBOR DEFENSE, NARRAGANSETT BAY

Last revision: 2030

Corrections, additions and comments are always welcome. Martin Dwyer; bhlaura @ webtv.net NOTE: To send me an e-mail, please delete the two spaces in the above address. Thanks!

All photos, unless otherwise noted, are from the collection of the above. Some of the basic data was published in a JAMESTOWN, RI. HECP STUDY prepared by VAROUJAN KARENTZ,

Army Mine Planting (Bouyant Mine)

"LET GO" @USA Singal Corps

1898 to 1900s In 1898, Narragansett Bay was one of 34 locations authorized for mine planting. (four of these locations were unable to plant mines before the decission to remove mines from Harbors and rivers was made in 1899. Army mine fields were planted in WEST PASSAGE of Narragansett Bay under the control of mining operations located at Fort Greble (Dutch Island, RI) and removed in 1899. Mine facility projects were developed in the 1890's, funded and constructed.

In 1898 Army mines were planted in EAST PASSAGE of Narragansett Bay under control of the Mining operations at Fort Adams (Newport, RI). Mines were removed in 1899.

Mine Wharf, Ft Adams c1910

@Npt Daily News

The Army mines were buoyant mines moored below the water surface. Buoyant mines with explosive charges of 100 to 150 pounds of dynamite (TNT) and spaced from 100 to 150 feet apart. They were clyndrical with cone ends, were attached by chains to anchors and floated about 15 feet below the surface. The mines could be set for "Contact Fire", Observation Fire" or they could be rendered "SAFE" by personnel, located at Mine Casemates, through underwater wireing. The contact firing options required that the target ship contacted the mine and tilted it, which in turned signaled the MIne Casemate. the signal could be selected to automatically fire the mine. If this option was not authorized then the signal would allert the Mine Casemate personnel who could , by order of the senior officer pressent, fire the mine. Observed fire required that the target ship be observed from a Fire Control Station (Mine Command Base End Stations) and fired upon directions from the Mine Plotting Room. When fired by shore personnel, the system was designed to exploding a set of mines (3 in a set).

Removal of a section of mines, NY Harbor c1898 @ National Archives

Pre Spanish - American War Mine case ruptured by the explosion of a neighboring mine (about 25 - 50 feet away). c1898 @ National Archives

Mine Casemate control of the East Passage was transferred from Ft Adams to Ft. Wetherill in 1908 and control of the West Passage was at Ft Greble until 1923, then transferred to Ft Wetherill. In 1937 the West Passage control was again transferred and went to Fort Getty (Jamestown, RI). In the early 1900s the Army switched to a spherical shaped mine which included a "Delayed Contact Fireing" in addition to the other three control methods described above in the 1898 - 1900 era. During the onset of World War I, there was a defensive plan at the Harbor Defenses of Narragansett Bay to lay 4 groups of 19 mines. Actual planting of these mines has not been verified at this time.

Army submaine mine from the early 1900s. Shows the mine cable going to the distribution box, then to the mine. The mine was held underwater by the anchor and anchor chain. @National Archives

Mine field tending vessels were supported by a complex of mine facilities including the torpedo storehouse, cable tanks, loading room, dynamite storage building and a Mine Casemate which controlled the firing of the mines. A new mine storehouse was built at Fort Wetherill in 1911 and many of the facilities were used and expanded during World War Two.

Inventory of Mine Command Supplies ~1920 * Buoyant Mines .................... 76 ea.( 4 groups of 19 mines) Anchors : ..... 1000 #.................................. 80 ea ....... 500 # ................................. 24 ea Juncton Boxes: ..... large .................................... 32 ea ..... small .................................... 30 ea Buoys: ...... Mine ................................... 76 ea ...... Marking .............................. 20 ea ...... Dist Box .............................. 4 ea Mooring Ropes: ...... 3/4" rope on 3/8" steel core . 6,400 feet ...... 3/4" steel rope ..................... 1,860 feet ...... 1/2" tared rope .................... 1,200 feet Test Set ..................................... 1 ea Cable: ...... 1 conductor ......................... 7.8 miles ...... 7 conductor ......................... 6 miles ...... 19 conductor ....................... 10 miles Planters (Govt vessels available) ...... ARNOLD ...... DUNN ...... DOWNS ...... SMITHY Dist. Box Boats (Govt vessel available) ...... L-30 Mine Yawls (Govt vessels available) ...... 4

* ref: Fort Record Book, Ft Greble

An Army Mine Planter c1943 @National Archives

An Army Mine Planter with one mine group ready for planting c1915 @ National Archives

In 1939 a fairly reliable mine system had been developed and by 1941 the Army finally had the material, adequate facilities, and trained personnel in positions at local mine depots along America's coast to begin deployment of mines in various defense areas including Narragansett Bay. On the eve of War World Two, the US Army Mine Planter (AMP) Brig Gen ABSALOM BAIRD was assigned to the 1st Coast Artillery District. This unit supervised the New England Coast Artillery Installations. I assume this was the vessel that initiated mineing operations at Narragansett Bay. Additional AMPs were constructed in 1942/43. By 7 December 1941 the Army had approximately 5,000 mine in stock and 1,200 mines in defensive minefield projects had already been planted. In early 1942, defensive minefields were completed in San Francisco, Portland, Boston, Narragansett Bay, New York, Chesapeake Bay, Portsmouth, Cristobal and Balboa (last two were located on the ends of the Panama Canal).

The 10th Coast Artillery Company (expanded to Regiment), Headquartered at Ft Adams, had units at Ft Wetherill, Ft Gety and Ft Varnum (RI) These units and their flotilla of mine vessels planted and controlled the minefields. East passage was controlled at Ft Wetherill and West Passage was controlled at Ft Getty until 1944.

Mine Field in East Passage of Naragansett Bay c1942 @Annex D, CCA-AN-NARB 38

Mine Groups I to V, West Passage of Narragansett Bay. Numbered from East to West c1942 @Annex D, CCA-AN-NARB 38

In 1943, a newer generation of mines replaced the some of the buoyant mines with M-4 ground mines. Ground mines lay on the seabed, filled with upwards of 3,000 lbs. on TNT. They were cone shaped, to resist being displaced by mine sweeping vessels. These new mines would signal the control panel if a ship over 1,000 tons passed over. The Casemate personnel could electrically fire the mines when given the authority, they could be placed in an automatic mode to detonate when it sensing mechanism detected a target or placed the mine in a Safe mode. There were twelve groups of M4 mines, 13 mines per group, six groups in each passage (East and West), in 1942 two lines were planted and placed into operation on 5 February 1942. Although a third line on mines was planned in the East passage, they were never planted. In postwar ordnance disposal summaries, it was reported, that at Narragansett Bay, 234 M-4 mines in total were recovered and disposed of in addition to 291 other types.

New ground mines on the forward deck, AMP MILLS @WClark

Titled: Model of Mines (used after 1943 ????? need to verify) @Navy Photo

Submarine Mine Explosion, @ National Archives

1944 - 1947 In 1944 a "Bombproof" bunker type "Underground" Mine Casemate was built at Hulls Cove north of Ft Burnside (Jamestown, RI) and the Mine Casemate operations were transferred there from Ft Wetherill and Ft Getty. All mines were connected by electrical cables to their respective shore Cable Huts (CH) "A" Hulls Cove and CH "B" Austin Hollow. Both CH A and CH B were connected to the Hull Cove Mine Casemate just west of Beavertail Road. The Hull Cove Casemate was a reinforced concrete structure where the locations on the mines and their targets were plotted and the mines were fired The underground structure contained mine target plotting and mine control operating rooms, where banks of light indicators and activation switches were located. The Mine Casemate at Hull Cove was under the direction of the Harbor Entrance Command Post (HECP) and via the Mine Commander Station at Prospect Hill. The HECP was to authorize and designate which mines to fire, to allow contact firing or be placed SAFE. One or more mines would be fired under Observation to destroy the intruder. Firing too many mines would open a path, which would allow intruders to enter the harbor after a false or decoy attack enticed the defenders to fire mines..

Harbor Entrance Command Post (HECP) Fort Burnside (Jamestown, RI @Navy Photo

There is no record of any enemy ship being damaged or sunk by any minefield which was located in the US areas. After WW2, the US Navy assumed the responsibility of harbor defense mining. Floating mines were actually deployed by German forces and posed a real coastal threat. Numerous mines were detonated and destroyed off the East Coast harbors including New York, Charleston (SC) and Cape Henry (Va.)

1947 - 2000s The Mine Facilities at Ft Wetherill still stand. The larger "Torpedo'" Storehouse at Ft Wetherill is used by the Jamestown, RI Highway Department as a garage and repair facility. The RI State Department of Environmental Management (RI DEM) is renovating three other buildings, the Mine Storehosee, Cable Tank and the Mine Loading Buildings, for Aquatac Research Center for Fisheries. A more recent proposal is being examined by the Jamestown Historical Society and the Friends of Fort Wetherill to establish an Interpretive Mine Center at the older dynamite storage building located up against the embankment.

The Hulls Cove Minie Casemate is presently located on private property and serves as a basemant for a private home. CH A and CH B still stand although deteriorating. CH A at Hull Cove still includes remnents of cable and connections.

A pre-WWII cylindrical buoyant mine case (type M-3) is displayed on a lawn at 200 Southwest Ave, Jamestown, RI. It was "planted" as a decorative commemoration in 1976 by Archie Clarke II.

48" Army Buoyant Mine Case, Jamestown, RI

REFFERENCES: Most of this information was taken from a study by Varoujan Karentz for the Jamestown Historical Society in April 2000. 'HARBOR ENTRANCE COMMAND POST - The HECP at Fort Burnside" Data was included based upon years of reading and talking with Coast Artillery Affectionados. Martin Dwyer - Retired Civil Servent US Navy, NETC Newport, US Air Force, March AFB and US Military Academy, West Point. Frank Kane - Coast Artilleryist National Archives Journal of the US Artillery