The Guns of Boston Harbor

Chapter X

The Duration (Part I)

Fort Independence, Castle Island

The Navy’s Castle Island Degaussing Station operated from 1942 to the end of World War II with a complement of ten to fifteen navy and civilian technicians. New electrical systems, including a deperming process that reduced (within certain limitations) the permanent magnetism of steel ships, were installed in mid-January, 1943. A navy barge with emergency generators, electronic apparatus, and personnel quarters anchored off a nine hundred-foot wooden pier on the southeast side of Castle Island constituted the deperming operation.

Fort Warren, George’s Island

Fort Warren’s main function during most of World War II was the control of the southern minefield. In late May, 1942, a new minefield of buoyant ovoid mines was laid and tested. In June, 1942, a disturbance in the outer minefield in Nantasket Roads alerted the evening operator at the Fort Warren mine casemate. His emergency call to the HECP at Fort Dawes brought the entire harbor defense system to full alert. Searchlights from Forts Revere and Warren and the outpost on Calf Island swept the water but the area was clear of surface vessels. First Naval District Intelligence immediately reported that no allied submarines were within two hundred miles of Boston Harbor. The mine casemate operators were puzzled as the sound of underwater propellers increased and diminished, but it became apparent as the target’s course was plotted that the unidentified craft was maneuvering adroitly through the newly planted secret minefield. The military authorities were distressed to consider the possibility that a spy or carelessness had compromised the minefield. Navy patrol boats were dispatched to form a line behind Fort Warren to block access to the Navy Yard if the apparently small submarine attempted entry.

As the unidentified craft turned through the fourth and final string, or line, of the minefield, one mine signaled that it had grounded. The mines were not set to explode on contact, but would fire only on electrical command by the Fort Warren mine casemate. Before the command to fire could be given the contacted mine, the undersea intruder reversed course and retraced its route back out of the minefield – an enviable example of seamanship!

Throughout the incident, rapid-fire gun batteries at the surrounding forts tracked the area and awaited orders to fire if a periscope broke surface. The order to activate the minefield or fire the artillery was never issued because the HECP wished to trap and capture the sneak-craft to discover where and how minefield data had been acquired. The answer to those questions as well as the identity of the intruder have not yet been found. Boston Harbor remained closed and on full alert for two days.

Although there were fluctuations in the underwater magnetic detection stations at Nahant and Strawberry Point later in the war, these were abnormalities in the systems and no other enemy sneak craft penetrated Boston Harbor.

In August, 1943, the Harbor Defenses mine project installed control apparatus for the new ground mine system. Ground mines rested on the seabed and could be exploded by contact, high magnetic influence, or by the mine casemate panel board. Battery D, 9th Coast Artillery Regiment (H.D.) (redesignated Battery D, 241st Coast Artillery Regiment (H.D.), in March, 1944) operated and maintained the southern minefield for the duration of World War II.

The old mine command building atop Bastion B was demolished and a modern reinforced concrete station was erected in its place. The Fort Warren mine station operated on a baseline with a new station constructed at Fort Revere. A highly restricted mine plotting room was installed in a casemate room under the John Brown Chapel and linked to the southern mine command and HECP at Fort Dawes. An airlock – secured by heavy steel airtight doors – opened into the mine plotting room, the chemical warfare service room, and a neighboring chamber converted to a latrine. Outside the gas-proofed rooms, another casemate chamber contained their generator and air conditioning systems.

In January, 1944, R.S. Brine Transit Company of Boston began removal of the two 12-inch gun tubes of Battery Stevenson to Boston Army Base where they were stored. The obsolete gun carriages were cut into sections and salvaged despite heavy winter snow and ice that made the salvage operation dangerously difficult.

Mine practice was held annually through 1945 at Fort Warren. New M- and L-boats were delivered to Battery D in 1944 but the mine planter Abbott remained the primary vessel. The Abbott also served the Harbor Defenses of Portland, Portsmouth, and Narragansett Bay on various occasions.

Due to Army redesignations, units of the 241st Coast Artillery Battalion (H.D.) garrisoned Fort Warren from October 1, 1944 through April 1, 1945. On April 1, 1945, another redesignation occurred and the 187th and 241st Coast Artillery Battalions were disbanded. Batteries A through E, Harbor Defenses of Boston then replaced the two battalions. When the war ended, the mines and cables of the southern mine command were deactivated and stored at Fort Warren.

Fort Strong, Long Island Head

Until the middle of World War II, Fort Strong controlled the northern mine group which contained more mines than the southern group. Mining command systems were transferred to more modern facilities at Fort Dawes and Greater Brewster Island, and Fort Strong’s mine casemate went to standby status. Fort Strong still handled minefield maintenance and received a new mine wharf, concrete runway, and boathouse in 1943. All Fort Strong’s major caliber guns were removed from Long Island or salvaged on site in 1943.

The formidable line of defenses atop the hill was now empty while wooden beams or metal plates covered the carriage wells. Fort Strong’s antiaircraft battery was modified with new directors, electrical appliances, and high rectangular sandbag enclosures.

Until October, 1944, Fort Strong was garrisoned by elements of the 241st Coast Artillery Regiment (H.D.). Due to Army redesignations, these troops became part of the 241st Coast Artillery Battalion (H.D.) from October 1, 1944 to April 1, 1945. When World War II ended, the mines and cables of the northern mine command were deactivated and brought to storage at Fort Strong.

Fort Heath, Winthrop

Early in World War II, two mobile 155-mm guns, emplaced in sandbagged field positions to the left of Battery Winthrop, exploited Fort Heath’s ideal location in the Boston Harbor Defenses. Until the 155-mm guns were withdrawn in 1944, they were constantly manned by a ready crew with the rest of the men on alert nearby.

In September, 1943, a special platoon-sized Mobile Group, equipped with tactical vehicles loaded with assorted weapons, maintained round-the-clock semi-alert status to meet any unusual emergencies at Fort Heath. 1943 also saw the establishment at the tip of the reservation of a Anti-Motor Torpedo Boat battery (designated AMTB Battery Number 945) of four 90-mm guns, two of which were in protected turrets on Model M3 gun mounts.

But the most noticeable sign of change at Fort Heath was the 1943 installation of a SCR-296-A long-range fire control radar. The radar screen was housed in a wooden cham