Twenty-four 155mm mobile guns were used in the Los Angeles area for beach defenses during WW II. These guns were moved by truck and could be rapidly set up on simple concrete circles known as Panama Mounts designed to stabilize the guns and provide a fixed location to aide in fire control.
 
The Panama Mounts were built at 13 locations in southern California between Santa Barbara and Costa Mesa and each location had facilities for shell storage as well as a makeshift barracks. The guns fired a shell that weighed about 90 pounds a distance of about 10 miles.
 

A battery of 155 GPF's at Camp Callen near San Diego

155 GPF in action at Camp Callen

• Construction Period:
  December 1941 - June 1942
   
• Cost of Construction:
  $6,500 - $19,000 depending on location
   
• Number of Carriages Built:
  Over 2000 for Coast Artillery and Mobile Use
   
• Number of Fixed Emplacements:
  About 300 in the United States and Territories

• Gun Type and Manufacturer:
  M1917 & M1918 155mm 37 Caliber
  Various Manufactures
   
• Total Weight of Each Gun:
  11.5 Tons for gun and Carriage
   
• Radius of Fire:
  180, 270, 360 Degree depending on location
  The 360 degree Panama mount is used exclusively around the HDLA area.

The Guns of Fort MacArthur