Fire Control (Aiming the Guns)

Fire control used a system of observation posts, plotting rooms, and command stations. Radar and listening devices were used to detect incoming aircraft, searchlights helped aim the guns at night, and observation planes flew out of Hamilton Airfield in Marin County. The Army and Navy coordinated the entire operation from the Harbor Defense Command Post at Fort Scott.

 

Each gun battery and offshore minefield had a set of observation posts, called base end stations, scattered along the coast. This drawing shows a section of a typical base end station and how two soldiers worked closely within the narrows confines of the structure. Many of these small dug-in "bunkers" can still be seen on the bluffs today.

Image courtesy of the Parks Conservancy

 

Soldiers used telescopes to determine the direction, or compass bearing, of enemy ships at specific time intervals. These men were trained to identify enemy ships only by their silhouettes (notice the training posters behind the men that show the different shapes of ships and submarines).

Photo courtesy of the San Francisco History Center, San Francisco Public Library

 

This photo shows a permanently-installed searchlight constructed at a ridge above the coast line. Both mobile and stationary searchlights helped to aim guns at enemy aircraft and torpedo boats during the night.

PARC, Golden Gate National Recreation Area

 

Data from base end stations was phoned to plotting rooms, where triangulation methods were used to plot a ship's distance, course, and speed with the help of trigonometric tables and analog computers. Based on this information, the battery command station phoned targeting orders to each gun emplacement. This photo shows Harbor Defense of San Francisco soldiers at the plotting room in Battery Davis, at Fort Funston.

Photo courtesy of the San Francisco History Center, San Francisco Public Library