Historic California Posts, Camps,
Stations and Airfields
Fort Rosecrans: Battery Thomas
(Battery Construction No. 126)
by Justin M. Ruhge
In 1940 the general staff approved the construction of two 16-inch
gun batteries and three 6-inch batteries as the primary ordnance
for the San Diego Harbor. The 16-inch batteries were to be casemated
and steel shields would protect the 6-inch guns.
In November 1941, the Chief of Engineers received funds for the
construction of a 16-inch gun battery at Fort Rosecrans. These
two guns, the largest type in the harbor defenses of the United
States, were the only ones in San Diego's defenses to be casemated.
Known first as Battery Construction No. 126, it was named in
honor of Major General Quinn Ashburn, who graduated from West
Point in 1897 and began his army career in the Artillery. He
won a Silver Star in the Philippines and a Purple Heart in France.
General Ashburn died in 1941.
The Macco Construction Company began work on the battery in June
1942 and completed it in March 1944 at a cost of $1,324,000.
The guns were proof-fired in July, but the steel shields did
not arrive until early 1945.
The guns were 816 inches long designated Model I Mark II Nos.
71 and 97 made by Bethlehem Steel and Watervliet Arsenal respectively.
They were mounted in March 1944 on high-angle barbette carriages
Model M-4 Nos. 31 and 39 made by Wellman Engineering Company
and Watervliet Arsenal respectively. The guns had a maximum range
of 48,000 yards at 47 degrees elevation and an effective range
of 44,000 yards or 25 miles at 41 degrees. The field of fire
was 145 degrees. The weight of the barrel was 146 tons while
the weight of the carriage was 39 tons. The base rings for each
gun weighed 84 tons. The two guns were mounted 500 feet apart.
Battery Ashburn served through the rest of World War II and was
declared surplus in May 1948.
Ashburn's plotting and switchboard room was built as a large
underground concrete structure to the north and east across the
road from the battery. Its command post was in the HDCP.
In February 1942, work began on the first of three 6-inch batteries,
referred to as Construction No. 238. V. R. Dennis of San Diego
won the contract in the amount of $128,000. This battery of two
6-inch rapid fire guns on barbette mounts protected by 2-inch
steel shields was located on top of Point Loma above the new
lighthouse. The design was similar to those already described
for the 6-inch batteries in the Bay Area.
The actual guns were Model M1903A2 Nos. 1 and 101 manufactured
by the Watervliet Arsenal. The carriages were barbette Nos. 100
and 101 manufactured by the Wellman Engineering Company.
Battery Humphreys was named in honor of Captain Charles Humphreys,
Fort Rosecrans' first Commanding Officer.
The battery was completed on October 14, 1943.
One of the two 16-inch guns
at Battery Ashburn. Note the woman included to show the massiveness
of this battery. Note the 2-inch steel shield under the casemate.
Photograph, Circa 1947 Courtesy of the Cabrillo National Monument,
A photograph of Gun
Emplacement No. 2's 16-inch gun at Battery Ashburn featuring
the length of the 50-caliber barrel. Photograph circa 1947, Courtesy
of the Cabrillo National Monument, San Diego.
Battery Ashburn in
1995. The Navy has converted the casemate into research laboratories.
Photograph courtesy of the U. S. Navy, San Diego.
Entrance to Battery
Ashburn, 1997. Photograph by the Author.
Completed Works - Seacoast Fortifications
Coast Defense Study Group
Plans For Battery
Ashburn, 1943 National Archives, RG 77, OCE, Box 129, File 600.914,