1937 target practice at a location that is now part of the
Marine Corps Base  at Camp Pendleton California.

During the first world war the US Army started looking at new ways to provide heavy mobile fire power to the Coast Artillery service. The use of railway mounted guns was nothing new at the time, the practice stated during the Civil war with both union and confederate forces mounting heavy cannons behind large wooden shields.

In 1925 the Baldwin Locomotive works released one of the worlds most advanced heavy railway guns. Four of the new guns were ordered by the US Army and upon

completion, two each were shipped to Los Angeles and the Panama Canal to augment the fixed defenses in those regions. The first of these new guns arrived in Los Angles to great fanfare, the gun's arrival at the opening of the new Union Station in Downtown Los Angeles was celebrated by an estimated 60,000 people.
 
The public's love for the big guns was short lived, while the army made every attempt to keep the public informed of the test firing schedule, the news often did not get communicated very well and the concussive nature of the test firings often caused heavy damage to local homes and businesses.
 
By 1928 the test firings became such a political issue that the War Department was forced to issue orders that no further firings would be permitted at Fort MacArthur. When the second gun arrived in 1929, it was quietly parked next to it's sister and the two guns quietly remained there until 1937.
 
Late that year, the two guns traveled south to a specially constructed railway siding on what is now modern day Camp Pendleton, where gun crews could train and the rifles themselves could be tested without causing damage to nearby property. The next year, would see the two guns leave Fort MacArthur for another training run, this time traveling north to the small town of Goleta, just north of the city of Santa Barbara. The guns of Battery Erwin were the longest ranging artillery pieces assigned to Fort MacArthur prior to World War Two and were capable of shooting a 1,450 pound shell up to 27 miles.
 
A unique feature of these guns was that they could be parked over a special prepared gun mount and have their wheels removed. This allowed the guns to turn 360 degrees and fire in any direction. This was a great advantage to firing on the tracks which limited the guns to a 7 degree traverse. This limitation was to prevent the force of recoil from exerting too much pressure on the tracks, which could cause damage and leave the guns stranded.
 
Both of Battery Erwin's guns remained active throughout World War Two but were declared surplus after the wars end and cut up for scrap sometime in 1946. 

The Guns of Fort MacArthur