13 inch Mortar
- Type: Model 1861 13 inch Siege & Seacoast Mortar
- Rarity: Uncommon
- Years of Manufacture: Between 1860 and 1864
- Tube Composition: Iron
- Bore Diameter: 13 inches
- Standard Powder Charge: 20 lbs.
- Projectiles: 200 lbs. Round Mortar Shells
- Tube Length: 56.5 inches
- Tube Weight: 17,250 lbs.
- Range (at 45°): 4,325 yards
- US Casting Foundry: Fort Pitt Foundry, Pittsburgh PA
- Special Notes: The mortar photographed at right is located in Ringwood State Park in NJ, Registry No. 27, Fort Pitt, 1861, and is noted for participating in the Seige of Vicksburg.
The 13" Union Seacoast Mortar saw action in many different theaters in the American Civil War. It was used by both the Army and the Navy. The official records site that four 13-inch mortars participated in the capture of Island No. 10. General Gillmore had a dozen, which took part in the reduction of Fort Pulaski, which protected Savannah. There were 20 mounted on schooners, which participated in the action against Fort Jackson and Fort Saint Philip below New Orleans. A 13-inch mortar was used to shell Fort Pillow and during the Yazoo Pass expedition a navy scow carried one which was used to shell Fort Pemberton.
This mortar was also very popular with Grant. He used them in both naval and land based batteries during the siege of Vicksburg. McClellan placed seven 13-inch mortars in Battery #4 at Yorktown. General Gillmore also used these guns to reduce Battery Wagner and Fort Sumter.
The 13-inch seacoast mortar had a maximum range of 4,300 yards. These mortars could be expected to be more accurate than their smaller counterparts.
One of the most famous guns of the war was the well photographed 13 inch "Dictator" which fired 200 pound mortar shells from a railroad platform propelled by 20 pounds of powder into the Confederate lines during the siege of Petersburg.