Yesterday I presented the three different 8-inch seacoast howitzers produced before the Civil War, noting the similarity to the Model 1844 Columbiad in the same caliber. Let me pick up discussion of those weapons now, noting the projectiles fired by those heavy howitzers and the weapon’s performance.
As alluded to in previous posts on the columbiad-seacoast howitzer family, the main employment of the seacoast howitzer called for the use of shells. The 1862 Ordnance Instructions specified the 8-inch shell weighed 49.75 pounds and measured 7.88 inches in diameter. While the shell could hold 2.5 pounds of powder, standard bursting charge was one pound. The seacoast howitzer shell was about a quarter-inch thicker than standard mortar or siege howitzer shells (which weighed under 45 pounds).
There is no direct specification on case shot for 8-inch seacoast howitzers. Presumably the cannon could use the standard howitzer case shot – weighing about 60 pounds, loaded with 486 lead balls and a 15-ounce bursting charge.
8-inch grapeshot consisted of nine six-pound, cast iron balls, each a maximum of 3.6 inches in diameter. The entire stand, with the iron balls, a top plate, two rings, a bottom plate, and a retaining rod, weighed 75 pounds! The other anti-personnel projectile, the 8-inch canister weighed 54 pounds. The canister consisted of forty-eight iron balls packed in sawdust.
Both the Ordnance Instructions of 1862 and the contemporary Artillerist’s Manual provided range charts with charges ranging from 4 to 8 pounds. However the listed service charge for the piece was 8 pounds. The columns on this chart indicate the powder charge, weight of shell, elevation in degrees and seconds, and the range in yards:
The figures above likely applied to the Model 1840 Seacoast Howitzer. The particulars listed for 8-inch seacoast howitzers in the 1862 Ordnance Instructions (table on page 20) match those for the 1840 model, and not the later 1842. And note the same table lists the Model 1844 Columbiad as a “shell gun.”
In confined waterways, the seacoast howitzer’s heavy shell could deter wooden ships of the day. But lacking the seacoast howitzer lacked the range to cover the wide channels common along the American shores. The range also limited the value of the seacoast howitzers to the Confederates firing on Fort Sumter in April 1861. While placing at least two of these howitzers on Morris Island, their role in the battle, if any, received little mention.
On the Federal side, three 8-inch howitzers covered the main harbor channel, deterring any ships approaching the besieged fort. While not directly noted, likely these were Model 1840 Seacoast Howitzers. More important for the fort’s defenders, one seacoast howitzer covered the sally port; and two more covered the esplanade and wharf on the south side of the fort. These three guns could sweep the wharf and approaches to the fort if the Confederates had attempted to storm the works. However these preparations proved excessive, as the Confederates compelled surrender without direct assault.
The employment of 8-inch seacoast howitzers at Sumter was perhaps the most noteworthy use of the weapon in the Civil War. Reports list the seacoast howitzers at several coastal forts and in the Washington defenses. However, these mostly provided close, anti-personnel defense until the 8-inch siege howitzer production picked up. The Rodman guns completely replaced the seacoast howitzers in the anti-ship role.