The Holland Torpedo Boat Company of New York City contracted Union Iron Works to build the two Plunger-class submarines.

For three and half years the two submarines operated out of Mare Island Naval Shipyard in San Francisco Bay for training and testing.

On June 10, 1917, work on land facilities started to offer quarters, mess hall, freshwater supply, ship fuel, and storage.

From August to November 1918 some new R-class submarines arrived after construction at Union Iron Works in San Francisco.

San Pedro Submarine Base and Long Beach became fleet anchorage for the 200 ships.

In 1940 President Roosevelt authorized the fleet at San Pedro to be stationed at Honolulu's Naval Base Pearl Harbor due to Japanese war actions.

The USS Farragut (TB-11) a training ship was based at San Pedro from 12 January 1915 to 14 April 1917.

San Pedro from 1919 to 1940 became the home port for some Navy ships of the Pacific Battle Fleet.

On August 11 First Lieutenant Jacob Zeilin leading US Marines and some US Navy sailors marched to the City of Los Angeles and captured it.

The US founded a military reservation in 1888 in an area surrounding San Pedro Bay as part of a harbor defense system.

San Pedro Bay port area was annexed to Los Angeles in 1909 and in 1913 a storm ended the Santa Monica operation.