After World War I, the versatile M1918M1 gun and its M1918A1 carriage were adapted for coast defense. Although the gun could be traversed over a wider range than other large guns of the period, it was still unable to adequately track moving targets. This deficiency was rectified by the development during the 1920s of circular concrete gun emplacements in the Panama Canal Zone. When emplaced on these simple, inexpensive, Panama mounts, the 155mm GPF was an effective alternative to older more complex coast defense weapons emplaced in large concrete batteries such as Battery Duportail’s 12-inch “Disappearing Rifles.” During World War II, two Battery F, 50th Coast Artillery’s 155mm GPFs were mounted on two Panama mounts that were constructed on top of Fort Morgan. The emplacement located on Bastion #4 is the last Panama mount at Fort Morgan.