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The chief advantage of the high trajectory coastal mortar was that it could provide plunging fire directly on the vulnerable deck of enemy warships from a good distance. The disadvantage was that they were less accurate than lower trajectory weapons and required a high rate of fire to improve the probability of hitting a moving target.

Twelve inch coastal defense mortars were initially deployed in batteries that typically contained two mortar pits with four mortars in each pit. The mortar pits were about 40' x 75'.

Each mortar pit of 4 mortars was manned by a pit section consisting of 88 enlisted men under a pit commander divided into four mortar detachments (14 men each) and a single ammunition detachment of 31 enlisted men.

As the coastal mortar batteries were built and tested it soon became apparent that the batteries were too crowded to safely support simultaneous firing and reloading of all four mortars. It was determined that two mortars could supply almost the same firing rate as four mortars in the standard mortar pit because they could be reloaded faster in a less crowded environment. Many of the batteries with eight mortars installed were reduced to four mortars by removing the #2 and #4 mortars from each pit. The excess mortars were either shipped to new batteries or left in place as spares. New mortar batteries were built with pits containing only two mortars.

Advances in ammunition saw the replacement of the blunt cap mortar shell with a new long pointed armor piercing shell. This shell was several inches longer than the blunt cap shell and required modification of carriers, hoists and widening of shell hoisting passages when it came into widespread use. The modification is generally referred to as the "long point" modification.