The Guns of San Diego at Cabrillo National Monument

A National Park Site becomes a Military Fortification in World War II

Massive 16-inch gun at Battery Ashburn at Cabrillo National Monument
Massive 16-inch gun at Battery Ashburn at Cabrillo National Monument

NPS Photo

Cabrillo National Monument served as one of a system of coastal defenses used by the War Department during World War II.  

History of the National Monument
Built in 1854 as one of the first navigational lights on the west coast of the United States, the lighthouse ins a prime historic resource at Cabrillo National Monument. It served mariners at sea and was a harbor light for San Diego Bay for thirty-seven years. Situated at an elevation of 422 feet, the light was the highest in the United States. From time to time high fogs dimmed its effectiveness, thus the light was abandoned in 1891 in favor of one at a lower elevation. The Army at Fort Rosecrans became responsible for the structure but allowed the lantern housing to deteriorate. Married noncommissioned officers and their families lived in the residence and there is a suggestion that one woman maintained a store of sorts around 1911, possibly for the many visitors who came out to Point Loma for the magnificent views. 

The site of the lighthouse became Cabrillo National Monument in 1913 and, while some commanders of Fort Rosecrans desired to remove the lighthouse, it remained standing.  The Department of the Interior acquired the monument in 1933 and the National Park Service carried out the restoration of the structure. A concessionaire occupied the building before and after World War II. The Interior Department permitted the Cabrillo National Monument to the War Department in 1941 and the Navy occupied the structure as part of its signal station for the duration of the war. During this period the white building was painted in camouflage colors. The Army made minor repairs to the building before returning it to the National Park Service in 1946.

In the early 1980s the National Park Service prepared a historic structure report for the lighthouse complete with recommendations. Further restorations have been carried out. Today the two-story, twenty feet by thirty feet, sandstone residence and the brick tower which it surrounds have been furnished to approximately the appearance of an 1887 keeper's home. It is an unmanned exhibit-in-place and a 134-year-old San Diego landmark.

Army Radio Station

Constructed in 1918, this small concrete structure was the Army's first radio station in the Harbor Defenses of San Diego. Among its duties was the challenging of vessels approaching the harbor during international emergencies. By World War II, army and navy radios operated from the harbor defense command post and the radio station became the meteorological station for the coast artillery. When National Park Service personnel manned the monument after the war, the superintendent established his offices in the building until the present administration building was erected under the MISSION 66 program. Today the building is used for storage. The building had three rooms: an operating room, motor-generator room, and sleeping room. Overall, dimensions are twenty-one feet, eight inches by fifteen feet, eight inches.

Battery Commander and Base End Station, BC3 and B1/3 S1/3, Battery Ashburn

Constructed during World War II, this concrete and steel fire control station was most important in Harbor Defenses of San Diego in that the battery commander of 16-inch-gun Battery Ashburn operated from the top level (BC3) directing the fire of his guns. The lower level (B1/3 S1/3) served as one of five base end stations for Ashburn. The roofs have been camouflaged to resemble large rocks. Steel rings on the roofs were anchors for camouflage netting. The steel shutters that protected the observation slits remain and the structure is in excellent condition. An exterior flight of concrete steps leads to the lower level.

Electrical Connection Box

This concrete connection box, part of the artillery fire control system, stands on the waterside of the Bayside Trail. Within the metal door is an aluminum box marked "1909 Engineers Department U. S. Army, Colin Electric Company, New York." On the exterior of the structure is "1941, U.S.A.," indicating that this box was installed as part of the modernization program on the eve of America's entry into World War II. The dimensions are: width, two feet, four inches; length, three feet, two inches; and height, three feet, eight inches.

Searchlight Shelter

This concrete shelter protected a 60-inch coastal searchlight. Engineers built it in 1918-1919. It is an above-ground structure built into a cliff on the land side of the Bayside Trail at an elevation of 218 feet. The searchlight was mounted on narrow-gauge rails that ran from the structure up the Bayside Trail about seventy-five feet to a point overlooking the entrance to San Diego Harbor. A short section of these rails remains within the shelter and protrudes under the door. The double door was wood framed and covered with metal. Earth and vegetation covered the flat roof blending the shelter into the hill above. The structure measures sixteen feet in length, twelve feet in width, and thirteen feet in height. Originally searchlight no. 5, it was renumbered 11 when additional lights were added in 1936, and in World War II it became searchlight no. 18.

Searchlight Generator Plant

The concrete power plant for searchlights 5 and 6 was built into a ravine between the two lights in 1918-1919. It had two rooms: a radiator room with two metal doors, that were opened for cooling, and two gassed windows above the doors; and the engine room that contained two 25 kw generating sets. The engine room had a wooden door leading to the exterior and two large, glassed windows. Today, one of these windows is filled in and the doorway has been doubled in width. The three remaining windows are now covered with vertical steel bars. When the building was constructed, two exhaust pipes emerged from the front of the structure and rose up over it. A part of one remains. Two ventilators stood on the flat roof which was covered with earth and vegetation. The dimensions of the structure are nineteen feet by twenty-nine feet. Two underground gasoline tanks in front of the structure have been removed.

Searchlight Shelter

The underground searchlight shelter, built in 1918-1919 at an elevation of 210 feet, contained 60-inch searchlight no. 6. The light was renumbered 12 in 1936, and 19 in World War II. The concrete pit is covered with a steel sliding door on rollers. This door or roof has a slightly sloped hip. Personnel access is through a steel-covered manhole and metal rungs embedded in a wall. The counterweighted elevator can still be operated manually with a chain sprocket drive. An original wood locker remains in a corner. The portion of the shelter that contained the elevator and searchlight is fourteen feet in depth, while the personnel portion is nine feet, six inches deep. The interior of the structure measures eighteen feet by ten feet, eleven inches. The shelter is several feet above the Bayside Trail and cannot be seen by passers-by.

Base End Station

The nearer of two fire control stations above the Bayside Trail near the north boundary of the monument was constructed circa 1920. It served as a base end station for the 10-inch guns of Batteries Wilkeson and Calef. It is an example of the first base end stations constructed at Fort Rosecrans. The flat roof was originally covered with earth and vegetation. Later, probably in World War II, the roof was covered with cemented boulders. Steel shutters cover the observation slits which are on two sides of the structure. A steel-covered manhole in the roof allows entrance to the station. Dimensions of the structure are six feet, ten inches by seven feet, ten inches, and six feet, six inches in height. On the floor is a low, concrete, octagonal base for a depression position finder. This station may be seen from near the north end of the Bayside Trail, but access to it is difficult and dangerous and damaging to vegetation.

Base-End Station

This fire control station, about twenty feet above the previous, was also built circa 1920. It is identical to the other in appearance. Besides the octagonal DPF base, the station still has the swivel bench the observer sat on. The station served either Battery Wilkeson or Battery Calef. When Calef-Wilkeson was abandoned in 1942, neither base end station 8 nor 9 was reassigned.

Commander's Station and Base End Station, BC6 B1/6, Battery McGrath

Located directly below the Cabrillo Statue, this fire control station was also built in 1920 and is identical to Nos 8 and 9 It served as 3-inch Battery McGrath's sole fire control station. McGrath was the only Endicott battery incorporated into the modernization of San Diego's harbor defenses.

Battery Bluff

Engineers constructed this two-weapon 37mm battery in 1942. It served as an anti-motor torpedo boat (AMTB) battery for the entrance channel. Each emplacement consisted of an arc of concrete three feet wide and two feet high on the inside. The eight bolts for a base plate, embedded in concrete, may be seen in the more northerly emplacement. Farther north, standing alone, is a four-foot steel pipe filled with concrete. When the battery was active, an azimuth instrument was mounted on this pipe. A short distance north of the pipe are two U.S. Coast and Geodetic Survey markers, both dated 1933.

Between the emplacements and to the rear is a circle of concrete three feet in diameter with a hole in the center about one foot in diameter. This object has not been identified as to function. Still farther to the rear is a depression in the ground. Nearby are fragments of window glass and plaster. South of the battery, across a gully, a square wooden box is sunk into the ground. It measures about five feet by five feet and about 2-1/2 feet deep. Still farther south at the mouth of a deep ravine lie the wooden ruins of an unknown structure. The battery can be spotted from the Bayside Trail but its function is not apparent to the casual visitor. Access to it is not permitted because of the delicate vegetation and already severe erosion, as well as the steepness of the terrain.

Battery Commander Station, Battery Humphreys and Base-End Station, Battery Woodward, BC5 and B1/5 S1/5

The two-level fire control station, immediately below the Whale Overlook, is of World War II construction. The concrete and steel structure has slightly domed roofs that have rocks cemented on them for purposes of camouflage. The observation slits are covered with steel shutters making them splinterproof. The upper level, BC5, served as the battery commander's station for 6-inch-gun Battery Humphreys. The lower level's observation room was Humphreys' No. 1 base-end station. The concrete octagonal platform for a depression position finder remains but the steel pipe for an azimuth instrument has been removed. Personnel entered the structure through a manhole in the roof of the upper level and an interior ladder led to the lower level. The rear room in the lower level was sometimes used as sleeping quarters. Visitors may view the structure from a short spur trail.

Base-End Stations for Battery Woodward, B2/1 S2/1, and Battery Grant, B4/10 S4/10

Almost identical in construction to HS-12 above, this fire control station served as base-end station to two 6-inch-gun batteries: the upper level, B2/1 S2/1, served Battery Woodward in north Fort Rosecrans, and the lower level, B4/10 S4/10, for the guns of Battery Grant at Fort Emory. HS-13, farther down a steep slope than HS-12, may not be visited due to erosion problems and physical danger to visitors.

Battery Point Loma

Because of delays in the modernization of San Diego's harbor defenses, the Army installed a battery of four mobile, 155mm guns 300 yards north of the new Point Loma lighthouse before World War II. Battery Point Loma covered the water areas to the west and northwest of San Diego. The guns arrived at Fort Rosecrans in 1939. Engineers constructed "Panama" mounts for the guns in 1941. After Pearl Harbor Point Loma became the challenge battery for the harbor defenses and the primary anti-submarine battery. The guns were removed circa 1943 when a 90mm AMTB battery was emplaced in the same area.

The four Panama mounts remain in place. Archaeologists have excavated emplacement no. 4 at the south end of the battery. The mounts were ninety feet apart, center to center. In the center of each emplacement was a circular concrete pad ten feet in diameter, on which the gun rested. Outside the pad was a circle of concrete, three feet wide and having a diameter of 38-1/2 feet. This complete circle allowed for 360 degrees traverse. A circular steel rail was embedded in the concrete on which the gun's trails rode.

An underground communications trench in the rear of the battery ran from gun no. 1 to gun no. 4. In the vicinity of gun no. 4 are three bunkers: one is about ten feet long and is made of corrugated, galvanized iron barrel vault, similar to a quonset hut; a second is approximately forty feet long and the corrugated, galvanized iron barrel vault is surrounded by a layer of concrete; the third bunker is similar to the first. The ruins of tunnels that connected these bunkers to the communications trench may be traced. Three additional bunkers are in the vicinity of gun 1. They are similar to those near gun no. 4.

While the one plan of Battery Point Loma does not show these bunkers, it is probable that the two bunkers covered with concrete were built as ammunition magazines but used as bunk rooms. Inside both of them are remnants of wood frames covered with chicken wire. These "bunks" have collapsed at gun no. 4, but are relatively sound at gun no. 1. The four other bunkers probably served as ready ammunition storage. The completion report for the similar Battery Imperial at Fort Emory said that underground shelters and magazines were constructed by troop labor.

Searchlight Shelter

Searchlight Shelter No. 15 is an underground shelter with a sliding, metal roof, similar to Shelter No. 6, above. It was constructed just west of Gatchell Road on the ocean side of Point Loma in World War II. Of the several searchlight shelters on the ocean side of the harbor defenses, this is the only one within the national monument.

Generator Station

This underground, concrete structure housed a generator set to supply electricity to the nearby coastal searchlight no. 15, above. Located about twenty feet to the west of Gatchell Road, it was entered through a door reached via a sunken, declined walkway. Because of vandalism problems, this walkway has been filled in and the door is not now visible. The interior condition of the plant is not known.

Bunker

Recently discovered, this underground bunker is 216 feet north of gun no. 1 of Battery Point Loma, and just east of Cabrillo Road. In general it resembles the bunkers at the battery. The top part of the structure is corrugated, galvanized iron barrel vault while the lower four feet of the walls are vertical concrete. The ends of the structure are concrete and there is a doorway in both ends. The bunker measures forty feet in length, ten feet in width, and nine feet, eight inches in height. There are wood-frame "shelves" or "bunks" with wire screen bottoms bolted to the concrete walls at the east end. The 1936 project called for the 4 gun, 155mm battery to have one magazine for projectiles, one for propelling charges, and a storeroom, all of permanent concrete construction, to be erected at the battery site. Presumably, this bunker was the storeroom, with part of it later converted to a bunk room.

Cistern

This cistern, in front of the old Point Loma lighthouse, stored water for the keeper and his family. It was one of two outdoor cisterns. The first one may have been constructed as early as 1858. The one now existing was an 11,000-gallon brick structure built around 1882. It was fitted with a Douglas hand pump and a suction pipe. At the same time a 2,900-square-foot catch basin was added. Today the cistern is capped with a dome-shaped concrete roof. The hand pump remains attached.

from Chapter 9: Guns of San Diego Historic Resource Study, Cabrillio National Monument, National Park Service, 1991