Dictionary of Fortification

Batteries, River and Coast Defense

Earthwork river and coast defense batteries were used quite extensively during the Civil War; very few navigable river in the southern states were not defended with some sort of fortification prepared for an artillery armament of heavy guns or howitzers. These river and coast defenses ranged from simple batteries to completely defensible semi-permanent field fortifications. In all cases their primary objective was to protect the artillery armament that was supposed to prevent enemy warships and logistical support vessels from passing up or down rivers or entering the harbors of important commercial seaports. Three significant naval developments turned ships' traditional disadvantage against land batteries upside down. Steam power gave ships the ability to sail faster and maneuver independent of the wind; armor plating gave them the strength to withstand almost any amount or weight of fire that land batteries could bring to bear against them while large caliber shell guns gave warships the means to attack and silence land batteries without necessarily being compelled to destroy their artillery armament or parapets.

Original Image Courtesy Coast SurveyShore batteries had very few resources with which they could counter these advantages. Well appointed batteries covering important points on rivers or the coast might receive an armament that included heavy smoothbore columbiads or large caliber rifled guns, but armored plating usually proved itself against these and the majority of river and coast defense batteries included a very high percentage of older 32-pounder sea coast guns. Methods for protecting the artillery armament were little different from those used for regular land service batteries, though the proportions of the various protective elements could be dramatically larger and thicker. Any advantages that shore batteries could obtain were gained by selecting particularly good battery sites where the armament could gain a positional advantage over enemy ships.

In general the armament of shore batteries could engage enemy warships using four basic types of fire: direct fire in which projectiles were aimed to strike the vertical surfaces of a vessel on the fly, ricochet fire in which projectiles were aimed at a point more or less short of the target vessel so that they could skip across the surface of the water to strike the vessel, and plunging fire in which projectiles were aimed to strike the less well protected horizontal surfaces of a vessel. Vertical fire from mortars was also used in an attempt to bust through the thin deck plating of armored vessels. This last type of fire was extremely problematical, but had the potential to sink a ship of piercing it through and blasting an irreparable hole in the hull. Direct fire could also be used to aim at the water just short of a vessel in an attempt to reach the hull and hole the vessel below its waterline. Direct and ricochet fire were least Original Image Courtesy Coast Surveyeffective against armored vessels, plunging fire was very effective, and vertical fire was the most effective, but was also the most difficult and depended a great deal more on luck than skill to achieve a hit.

A good position was of the utmost importance for a land battery to successfully engage attacking armored warships with any of the four types of fire. Direct and ricochet fire required that the battery be positioned fairly close and just above the level of the water. Plunging fire had to be delivered from a well elevated position that looked down on the water. Vertical fire could be delivered from any convenient point regardless of elevation in relation to the level of the water. It was almost always better to place earthwork batteries well back from the shore line, preferably near and below the crest of a natural rise so that the ground itself could be used to increase the protective cover of the battery position and make it more difficult for ships' crews to judge the fall of their shot or distance of shell bursts.

Original Image Courtesy Library of CongressIt was not enough to simply site batteries at appropriate elevations in relation to the level of the water, after all, river and navigable streams tended to rise and fall with the seasons; a battery placed to give a direct fire on a river channel in winter might be limited to plunging fire when the water level fell in the summer. A second important consideration for the success of land battery was their position in relation to the direction of the channel through which warships would be forced to travel as they approached the land battery. An ideal position would compel advancing warships to engage a land battery with its bow guns alone while the battery could engage the ships with its full armament. This was a condition that was difficult and sometimes impossible to achieve, particularly for coastal defense batteries that faced the open ocean. But sinuous rivers usually presented any number of excellent positions, especially on meandering bends, where warships could be placed in relatively disadvantageous positions during the initial stages of their attack.

It was also important to establish more than one battery to oppose the passage of warships through a guarded channel. Several batteries firing at the same target from different angles and elevations had a better chance to cause sufficient damage to disable or compel ships to abandon their enterprise. This also tended to divide ships' fire and prevent them from concentrating on a single battery; when one battery was silenced, two or three others would still be in action and when the ships shifted their fire to silence them, the guns of the silenced battery could be remanned and return to action. When more than one battery was established to fire on a section of a channel chances were that at least one battery would have a positional advantage over one or more of the attacking ships throughout the action.

This was one of the weaknesses of America's third system casemated coast defense castles: their batteries were concentrated on fronts that were generally only about 100 yards long, quite often less, which allowed steam powered warships, armored or not, to run the batteries and clear the range of the fort's guns before Original Image Courtesy Library of Congresssuffering a significant amount of damage. In no case during the Civil War were these forts capable of stopping a fleet determined to run past them; but this was also true of earthwork river defense batteries. Bringing such an attempt to a halt required obstructions in the channel that ships simply could not avoid or pass through. Confederate engineers tried a number of different means to block river and harbor entrance channels with varying degrees of success. Heavy chains were used at Columbus, Kentucky and at the Plaquamine Bends below New Orleans; sunken transports were used on the James River in front of Fort Darling and at various other places. Torpedoes (or the threat of torpedoes) were also used with more or less success to prevent Federal ships from even attempting a passage.

January, 2004