Mortars

The mortar is a snub-nosed, smoothbore weapon designed to hurl a ball a great distance into the air so it falls almost vertically into an enemy position. Usually mounted on heavy wooden beds most fell into the definition of siege or heavy artillery, although some were relatively small. The rounds fired were largely designed for use against personnel rather than objects sucli as masonry walls or enemy artillery. Hence, the preferred ammunition included shells (the primary round), grape, light and fire balls, and carcasses.

According to Colonel I lenry Scott's 1861 Military Dictionary: "The following mortars are used in the United States service: The heavy 13-inch mortar, weighing 11,500 lbs., the whole length 53 inches, length of chamber 13 inches, and superior diameter of chamber 9,5 inches; the heavy 10-inch mortar, weighing 5,775 lbs., whole length 4(> inches, length of chamber 10 inches; the light 10-inch mortar, weighing 1,852 lbs., the whole length of mortar 28 inches, length of chamber 5 inches; the light 8-inch mortar, weighing 930 lbs,, whole length of mortar 22.5 inches, length of chamber 4 inches; brass stone mortar, weighing 1,500 lbs., diameter of bore l(> inches, whole length of mortar 31.55 inches, length of chamber 6.75 inches; brass Coehom 24-pounder, diameter of the bore 5,82 inches, weight 164 lbs,, whole length

A 16-inch Rodman gun at Fort McHenry National Park, Baltimore. These guns served as weapons defending the city through World War I.

A 16-inch Rodman gun at Fort McHenry National Park, Baltimore. These guns served as weapons defending the city through World War I.

16,32 inches, length of r ham her 4.25 inches; iron eprpuvette, diameter of the bore 5,655 inches, weight 220 lbs., length of bore exclusive of diameter, 11.5 inches, length of Chamber, 1.35 inch. Mortars are mounted on beds, and when used, siege mortars are placed on a platform of wood made of 6 sleepers, 18 dec k planks; and 72 dowels; fastened with 12 iron eye-bolts."

The M1861 10-inch mortar used a charge of one pound six ounces of powder to fire a 104-pound round (27 12-pounder iron canister halls and a bursting charge of 2.5 pounds of powder), 800 yards with a 13-second fliglu. Lieutenant^Colonel Joseph R. 1 lawley, 7th Connecticut, watched the mortars in use at the siege of Fort Pulaski, Georgia. According to him: "... the twelve big mortars will each fire five times an hour (ii is a slow job to clean, toad and aim them ) making 60 shells an hour. Each mortar gives two reports, the firing of the mortar and the bursting of the shell," In order lo give the mortar some mobility during the siege of Petersburg; Union forces used a novel system. According to one of their artillerymen; "The great weight of the 13-inch mortar (17,000 pounds) renders ii difficult to move and some satisfactory experiments were made with a novel platform. An ordinary railroad platform car (eight wheels) was strengthened by additional beams tied sironglv by iron rods and was plated on top with iron. The mortar was placed upon the car (Lop of mortar nine feet above the tracks) and run clown on the Petersburg and City Point Railroad to a point hear our lines where a curve in the track afforded facilities for changing the plane of fire by advancing the car or drawing it back,

"The mortar fired with 14 pounds of powder recoiled less than two feet on the car which moved 10 or 12 feet on the track. The effect of the c harge was taken up without damage to the axles, even when a full allowance of 20 pounds of powder was used ...

"iLs practice was excellent ... of course with this platf orm, the plane of fire must be nearly paralleled to the track or the mortar will be dismounted, but by placing the car on a curve, a very considerable traverse can be secured without difficulty.'*

The light mortar most used during the war was the M 1841 bronze Coehorn mortar, which weighed about 296 pounds on ¡is bed (164 pounds for the tube alone), fired a 24-pounder shell, with a half-pound powder charge, some 1,200 yards. It was manned by a crew of four.

Tredegar cast its first mortar, a 10-inch model, in July, 1862, the first of 10 made that year. Another eight were cast in 1863, five in 1864, and one in 1865 for a total of 24 10-inch mortars. It cast its first 8-inch mortar in February, 1863, and thereafter cast a total of 15, most in late 1864, The Richmond-based foundrv was the only major source of Southern-made siege mortars, although a private company, S. Wolff & Co., produced two 10-inch mortars in New Orleans. These were tossed into a canal basin on the fall of that city. A.N. Miller, a foundry in Savannah, produced one 15-inch and three 10-inch seaCoast mortars in 1862 for that city's defenses. The Selma Naval Gun Foundry, Alabama,

Artillery Battalion Organization

Another view of one of Fort McHenry's 16-inch Rodman guns. They are placed in a fortification outside the main fort, which is in the background.

produced 19 Coehorn mortars.

Confederate makers also produced a 12-pounder iron Coehqrn mortar which they felt was an effective weapon. According to one Union artillery officer who examined a captured version of this weapon: "For practice against troops, the 12-potiinder Coehorn is decidedly more deadly than the 24-pounder as its shell, when the fuse burns too slowly, does not bury itself on striking and the fragments thus scatter widely."

I n 1866, the Army of Northern Virginia corps artillery chief, E. Porter Alexander, described the variety of mortars Southern field armies used: "During the siege of Petersburg a number of iron twelve and twenty-four pounder Coehorn mortars were made and rendered excellent service. Wooden mortars were also made and tried for short ranges, but even when they did not split, the ranges were so irregular that they could not be made useful." Confederate artillerymen at Petersburg ran short of friction primers but continued firing their mortars bv heating priming wires red hot and inserting them in the vents.

Mortars were useful in siege situations, but were not always available to field armies. Therefore, artillerymen often improvised by using tree trunks for their mortar tubes. According to a Union report of the siege of knoxviile: "The repeated assaults upon this fort, and the close proximity of the enemy's rifle-pits, made it very desirable to mount two or three mortars for the purpose of shelling out the enemy's trenches. As none were on hand, a wooden mortar was constructed, Capable of throwing a 24-pounder howitzer shell. It was made of a live white oak, 2 ¡7 feet in diameter, and when finished, the thickness of the wood was 1 foot and in rear of the seat of the charge from 18 inches to 2 feet, h was hooped with three iron bands shrunk on, and mounted on a bed of oak. It was fired with a 24-pounder howitzer shell and 7 ounces of powder, and withstood the test admirably; but subsequently, being fired with the same projectile and l(i ounces of good powder, it burst in two."

Another view of one of Fort McHenry's 16-inch Rodman guns. They are placed in a fortification outside the main fort, which is in the background.

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