US Navy Mortar Schooners shattered Fort Jackson in 1862.
US Navy Bomb Vessels
Photo of a bomb vessel of the type that blasted Forts Jackson and St. Phillip on the Mississippi River, 18-23 April, 1862. Captain David Porter commanded twenty-one of these US Navy mortar schooners during the attack. Flag-Officer (later Rear Admiral) David Farragut held overall command of the operation.
The use of “bomb vessels” by naval units was not new. The concept dated back to the 16th century.
Mechanics of mortars
The use of mortars on naval vessels was not much different than their use on land. Mortars shot small bombs into the air at high angles. Those bombs were fuse-activated. So, the gunner prepared the shells. The crew loaded the mortar itself with gunpowder and wads. When given the order to fire, the crew lit the bomb’s fuse and dropped it into the mortar. They touched the fuse-hole, igniting the gun’s powder. The bomb shot up, arced to the target, and exploded when the fuse burned down.
The trick was in the fuses. Cut the fuse too short, the bomb blew up before reaching the target. Cut it too long, and the bomb landed on the target, unexploded. Anyone around the bomb could pull the fuse out and extinguish it.
C. S. Forester wrote a fantastic scene about the siege of Riga, in 1812, in his novel, The Commodore. If mortars interest you, you’ll enjoy that story.
Success at Fort Jackson
Porter learned his bomb fuses on his US Navy mortar schooners were problematic on the first day of bombardment. Many of the bombs exploded in the air, before reaching the fort. To counter this, Porter ordered that fuses not be cut. Many of the bombs landed in and on the fort. The high-water conditions along the Mississippi River made for soggy ground in the fort. So, when the bombs landed, they hit mud and sunk in. This extinguished the fuses. Porter’s vessels fired nearly 7500 bombs. Of those, over a thousand were found in the ground when Union troops entered the fort.
Damage and mutiny
Despite the high number of unexploded bombs, Porter’s attack damaged the fort and demoralized its garrison. Flooding inside the fort presented a challenge for the rebels. If they stayed in the open, they risked injury from the bombs. If they took refuge in the casemates, they were stuck in flooded areas. This contributed to the mutiny of 28-April-1862 by Irish and German troops.
USS Cayuga participated in Farragut’s attack on Forts Jackson and St. Phillip.
An Unadilla-class gunboat, Cayuga was launched on 10-Oct-1861, at Portland, CT. After final fitting-out at the New York Navy Yard, she was commissioned on 21-Feb-1862. Upon commissioning, the Navy ordered Cayuga to Ship Island. The gunboat joined the West Gulf Blockading Squadron. Flag-Officer (later Rear Admiral) David Farragut commanded that squadron. Cayuga was one of nine Unadilla-class gunboats in the squadron. After the rebel army abandoned New Orleans to Farragut and Butler, Cayuga remained in the squadron, moving north to support operations as Union forces secured the Southern portion of the Mississippi River.
Farragut’s nine Unadilla-class gunboats engaged rebel boats along the river at Forts Jackson and St. Phillip. They were:
The rebel defenders extended chains across the river, from one fort to the other. On 20-April-1862, Farragut ordered three of the Unadillas up the river to clear those chains. They opened a passage on the west side of the river. Farragut moved the rest of his squadron, including Cayuga, up through this opening.
While Porter’s mortar-vessels pounded the forts, Cayuga and the other gunboats blasted a path for the larger ships in the squadron. Cayuga and the other five gunboats that cleared the forts anchored in the river at New Orleans. Their firepower compelled the surrender of the city. So, the gunboats threatened New Orleans with flooding. Their guns could take aim at the city’s levee system. City leaders knew the impact crevasses would have.
Captain Theodorus Bailey held command of Colorado, 19, as part of the West Gulf Blockade Squadron. Bailey and Colorado enjoyed success off the Louisiana and Mississippi coasts in the early months of 1862. He was, however, unable to bring Colorado up the river. While Colorado was a significant asset, the frigate’s draft was too deep. So, Farragut transferred Bailey from Colorado to Cayuga for the attack. Bailey commanded a division of three gunboats. He successfully brought Cayuga into the Port of New Orleans. On 25-April-1862, Farragut ordered Bailey to enter the city. He and Lieutenant George Perkins, USN, went to City Hall, where their surrender demands were rebuffed.
This image appeared in Battles and leaders of the Civil War : being for the most part contributions by Union and Confederate officers, Volume 2, 1887.
Mississippi River defenses in 1862 consisted of Forts Jackson and St. Phillip.
Mississippi River defenses
Library of Congress title: Map showing the defenses of the Mississippi below New Orleans and Farragut’s attack 24 April 1862. This hand-drawn map presents a great deal of detail about Forts Jackson and St. Phillip. Additionally, it displays the positions of Farragut’s ships as they approached Fort Jackson. Robert Knox Sneden drew the map.
Attacking the forts
While the blockade of the Gulf Coast crippled the economy of New Orleans, the forts below the city prevented the Union Navy from moving upriver easily. The Union Navy sent Flag-Officer David Glasgow Farragut, along with Captain David Dixon Porter, to the Gulf. Farragut held overall command. Porter commanded a flotilla of bomb-vessels. Additionally, Major General Benjamin Butler led an Army invasion force from Ship Island to the forts.
Fort Jackson, on the west bank of the Mississippi River, stands below Fort St. Phillip. So, it was the squadron’s first target. Porter’s bomb-vessels approached Fort Jackson. They fired thousands of mortar rounds into the fort. Those mortars wrecked much of the fort. They demoralized the garrison. The assault contributed to the mutiny of Irish and German soldiers in the fort.
Robert Knox Sneden
Sneden created this map after the rebellion. In the Spring of 1862, he served served on the staff of the Union III Corps, under Samuel P. Heintzelman. He was later captured and held at the notorious Andersonville prison camp. In his roles of draftsman and topographical engineer with III Corps, Sneden drew thousands of sketches. After the war, he created watercolor works out of those sketches. While he was not present with Farragut’s squadron, Sneden had the skill to turn the descriptions of others into maps.
This colorized sketch is not a hi-res document. It likely came from a small sketch book.
Fort Jackson Bombardment by Farragut’s squadrons took place in April 1862.
Click image for larger sizes.
Fort Jackson Bombardment
The title of this map is, “Plan of Fort Jackson, showing the effect of the bombardment by the U.S. mortar flotilla and gunboats, April 18th to 24th 1862 : flag officer D.G. Farragut commanding fleet, Com. D.D. Porter commanding flotilla.” This map displays the aftermath of several hellish days and nights of cannon shot and mortar bombing on the fort. The Union Navy delivered strong blows. Two rebel battalions, one Irish, one German, mutinied. They walked out of the fort and surrendered to Butler’s invasion force.
The map shows the fort oriented towards the north. The Mississippi River barely appears here at the top of the image. Fort Jackson stands (to this day) on the west bank of the river in Plaquemines Parish.
J. S. Harris surveyed the Fort Jackson Bombardment in the days after the assault. Farragut’s advance to the Port of New Orleans led to the city’s surrender. Butler and his force occupied the city by 1-May-1862. While there is no specific date on this map, the survey likely took place after 1-May. The comments speak to the intensity of the attack:
All the scows and boats near the fort except 3 small ones were sunk. The drawbridge, hot shot furnaces, and fresh water cisterns were destroyed. The floors of the casemates were flooded, the levee having been broken. All of the platforms for pitching tents on were destroyed by fire or shells. All the casemates were cracked (the roof in some places being entirely broken through) and masses of brick dislodged in numerous instances. The outer walls of the fort were cracked from top to bottom, admitting daylight freely.
4 guns were dismounted 11 carriages and 30 beds and traverses injured.
1113 mortar shells and 87 round shot were counted in the solid ground of the fort and levees.
3339 mortar shells were computed to have fallen in the ditches and the overflowed parts of the defences.
1080 shells exploded in the air over the fort.
7500 bombs were fired.
We’re going to have to do a full long-form article on just how exstensive this damage is. It comes as no surprise that the Irish and Germans who survived this walked out.