25) War Diary of the Eastern Sea Frontier
Dec 1941- Sept 1943
(Selected Excerpts Pertaining to the Defenses of the Southern New York Harbor)
Updated: October 23, 2000 (HTML code changes)
Poor pre-war defensive planning, not "a careless word"
led to the sinking of many ships by a few German
submarines just offshore America's Eastern Sea Frontier.
(Source: National Archives and Records Agency)
The Army and the Navy developed sophisticated anti-submarine detection
systems to combat the German U-Boats that were attacking shipping close
to the shore and inside America's harbors on the East coast from January
of 1941 to July of 1942.
The Army maintained many fire control base end stations that were used as
lookout posts. Patrol planes of the Navy (as well as Navy blimps), Army,
Coast Guard, and the volunteers of the Civil Air Patrol were assisted by
sightings from Pan Am Clippers and other airliners spotting submarines,
sinking ships, oil slicks, or liferafts. Coast Guard Stations and ships,
as well as fishing and
merchant vessels, also made similar reports.
Magnetic detection loops were laid along the bottom of the New York
Harbor in the Ambrose Channel to detect submarines that could not be
detected by the newly developed radar system. The SCR-582 harbor
surveillance radar was used to detect targets at night and in poor
visiblity conditions. The SCR-296 fire control radar was used to
determine precise bearings and ranges for gun batteries. B-17 aircraft
from Mitchel Field were equipped with radar sensitive to detect the
periscope of a partially submerged U-Boat. Other aircraft were equipped
with MAD (Magnetic Anomaly Detection) equipment that not only detected
submarines, but often detected the wrecks of ships that were previously
sunk by German submarines.
Radio Direction Finding (RDF) sets were used by the Army, Navy, Coast
Guard, and the FCC to triangulate on the Enigma encrypted radio signals
sent by the German U-Boats. RDF stations were established at Jones
Beach, LI, Sea Isle City, NJ, Montauk, LI, as well as other locations
along the shore. These RDF stations (and other radio stations) not only
intercepted German radio traffic, but
also the SSS signals (send help, ship torpedoed) from ships that had
become the victims of the U-Boats.
Underwater listening equipment called "hydrophones" were connected to
shore based stations. They were also dropped from blimps and ships to
listen for submarines. Sonobouys were later installed to act as remote
listen stations. The type JN-1 sound ranging equipment was later used by
ships to determine the distance to the targets detected.
Contact minefields were laid in the New York Harbor. These minefields
were set to the "contact mode" when a loop or hydrophone detected a
possible submarine. The mines would then indicate to Army personnel
stationed in a Mine Casemate bunker when they were struck by a ship. The
mines could then be detonated by the Mine Casemate to destroy the enemy
When a loop or hydrophone detected a possible enemy submarine in the
harbor, a submarine net located at the Narrows between Fort Wadsworth in
Staten Island and Fort Hamilton in Brooklyn was closed. A net tender
vessel was stationed at this normally open net, and closed the net upon
orders from the Harbor Entrance Control Post (HECP).
In addition to the US Army using mines, German submarines laid mines in
the New York, and other American harbors. Minesweepers would routinely
conduct mine sweeping operations to keep these harbors safe for friendly
All of this information was collected and plotted on a daily basis, by
Naval Personnel of the Eastern Sea Frontier Command at 90 Church Street
in Lower Manhattan. The Army and Navy jointly operated the Harbor
Entrance Control Posts (HECPs) at all protected harbors.
The Eastern Sea Frontier Headquarters at 90 Church Street
The harbor defenses of Southern New York were controlled by one HECP at
Fort Wadsworth in Sataten Island, NY, an Advance HECP 1 at Fort Hancock
at Sandy Hook, NJ, and an Advance HECP 2 at Fort Tilden in Rockaway, NY.
Click here for more details about Fort
The following excerpts pertaining to the defenses of the Southern New
York Harbor were derived from the "War Diary" of the Eastern Sea Frontier
from Dec 1941- Sept 1943. This document is available on 7 reels of
microfilm at the Naval Historic Research Center, Washington Navy Yard
(Item reference NRS 1971-48)
1/31/41 -- At NAS NY, Floyd Bennett Field, twelve OS2U-3 and three J2F-5
patrol aircraft were each equipped with 2 MK-XVII depth bombs.
2/14/42 to 2/21/42 -- Anti-aircraft gun training will be conducted at
Fort Tilden between 100 and 130 degrees true, out to 20,000
3/4/42 -- A submarine was sighted 1.5 miles offshore at Beach 97the
Street in Rockaway heading westbound. Seven patrol vessals responded to
patrol the area with negative results.
3/31/42 -- At Mitchel Field on Long Island, the US Army had the following
aircraft available for maritime patrol, three B-18 and four B-25
4/11/42 -- Squadron VS1D3 at NAS NY, Floyd Bennett Field, had eighteen
OS2U-3 aircraft, and the Coast Guard had nine OS2U-3 aircraft available
5/1/42 -- A Navy plane from NAS NY, Floyd Bennett Field attacked a
periscope off Fire Island, Long Island.
5/17/42 -- A type 122 electric mine washed ashore at West 57th Street in
Coney Island, Brooklyn and was recovered by the police.
5/21/42 -- 0430 Hours, HECP (Harbor Entrance Control Post) reported a
signature on loop 2B (Rockaway and Ambrose). Craft identified as on
surface. Being investigated by Navy.
6/1/42 -- Police informed ComThree that a metal cylinder, possibly a
mine, had been found on the beach at Rockaway Point, L.I.
7/14/42 -- "2030 Hours, Policeman and Army observer reported sighting sub
one mile off Rockaway Beach, L.I. Several boats were sent to investiagte
and found nothing. PC-64 was in area and might have been mistaken for a
sub. Water is shallow for some distance off shore with depth about 30
feet at one mile off." (Note: PC is a Navy designation for a minor war
vessel used as a Submarine
8/25/42 -- "2115 Hours, Radio Operator, H.E.C.P. Fort Wadsworth reported
having heard unidentified vessel calling CORA, (the call for any naval
aircraft at scene of action). Vessel reported it had contact or was
attacking 080 degrees True, 43 miles from Cholera Bank. Position is about
40 35N; 72 30W. Unable to obtain further information"
9/26/42 -- CGR-4331 reported a floating mine 1/2 mile off Rockaway Inlet,
NY. (CGR is the designation for a type of Coast Guard Vessel)
10/13/42 -- Unidentified signal on loop in vicinity of Ambrose, not on
radar. Position 1 and 3/4 miles NW of Ambrose.
10/23/42 -- EDC reported contact on loop 2B. Nothing found.
10/29/42 -- CGR reported wake 40 33N; 73 46W, 2 miles South of East
11/13/42 -- "1117 Hours, YMS-20 witnessed inder water explosion two miles
from Ambrose in 40-25-42N; 73-44-00W, bearing 170 degrees True from
minesweeper, range 300 yards. YNS-20 considers explosion actuated by
reverse pulse. Column of water 200 feet high was seen. EDC reports all
Army mines have been accounted for. Explosion evaluated as magnetic mine
or old depth charge. Port entrance closed until 1800/14 while twelve
minesweepers operate in area".
11/8/42 -- HECP Wadsworth reports vessel CARETTA collided with net at
11/17/42 -- 0844 Hours, Unidentified medium sized vessel signal on loop
2B. Also at 1103 Hours, a medium sized vessel outbound, at 1111 Hours a
medium sized vessel outbound, and at 1116 Hours a medium sized vessel
inbound. Visiblity poor.
11/24/42 -- 1448 Hours, Unidentified medium sized vessel signal on loop
2B. Possibly one of 3 minesweepers in area. At 2109 Hours, an
unidentified small sized vessel signal on loop 2B in Ambrose. Radar
cannot classify. HECP reports target is outbound at 4 knots. CG 83342
was sent out and nothing was found.
11/25/42 -- An unidentified small sized vessel signal on loop 2B in
Ambrose. Radar unable to identify.
11/27/42 -- CGC 494 reports strong contact off Ambrose and then
11/30/42 -- "0439 Hours, EDC received report from HECP NY that between
0439 and 0511 five unidentified vessals were coming in over loops 2A and
2B. Gate immediately alerted to close. Position of vessels: Azimuth 175
S 19,000 yards. Range from Water Witch radar station. At 0625 gate was
ordered closed. Harbor defenses alerted. Blimp and 5 SC ordered to
search. Gate was reopened at 0800."
12/2/42 -- Unidentified signal on loop 2B at Sandy Hook.
12/5/42 -- Unidentified small signal on loop 2A, no radar
1/17/43 -- HECP NY reported Sonobouy 14 and 16 recorded small signature
at 2230 and 2231. Gate closed 2318 until it was reopened at
1/29/43 -- Mines wash ashore at Monmouth Beach and Asbury Park.
2/27/43 -- HECP NY reported that CG 38477 (38 foot) ran into gate
obstruction north of YNg3 (Gate Tender). She was abandoned and sunk in
30 feet of water.
3/29/43 -- Explosion onboard ESSO MANHATTAN, unknown causes. Port
closed, later reopened on 3/30/43 at 0915. Explosion was determined to
be from onboard and not caused by mine ortorpedo.
4/1/43 -- The following aircraft were stationed at Floyd Bennett Field in
Brooklyn (NAS NY): Squadron VS34 with eighteen OS2U-3, and one J4F-2.
Squadron EAD with one JRF and one J2F-5, Coast Guard with three J4F-1
and one PH. At Mitchel Field the Army had seven B-18-R and four B-24
4/20/43 -- PC-1169 reported floating mine in Chapel Hill Channel (North
of Sandy Hook). Recovered and identified as an Army mine. Three more
mines washed ashore between Sandy Hook and Belmar, NJ. A fourth,
additional mine was found 1/2 mile off shore inside of Sandy
8/1/43 -- The following aircraft were stationed at Floyd Bennett Field:
Squadron VS34 with eighteen OS2U-3, one J4F-2, and two So3C-2, Squadron
VB128 with twelve PV-1, EAD with 1 JRF-5, and the Coast Guard with one
PH-3, three J4F-1, one JRF, and six S03C.
8/7/43 -- PV-1 (P-9 of VB128) from Floyd Bennett Field, Brooklyn found
and attacked an enemy sub. The plane was shot down by the sub within 15
miles of 37-35N; 71-20W. The crew of two was wounded and picked up by a
PBM aircraft. At NAS Lakehurst, there were eleven type ZNP blimps, and
at Mitchel Field in Long Island, the Army had nine B-17 and one B-34
8/19/43 -- What was believed to be an Army mine was recovered in
Rockaway Inlet by CG-83345.
9/26/43 -- An OS2U aircraft from Floyd Bennett Field crashed 7 miles S of
Little Egg Inlet (Near Atlantic City, NJ). Two survivors were picked up
by CG 83340.