Two sieges for the price of one! Gillmore’s evolving plans on Morris Island

From the moment the first assault wave rowed ashore on the southern end of Morris Island, it seemed that Brigadier-General Quincy Gillmore’s plans shifted like the sands on the beach. The original plan called for a four phased campaign to secure the Navy’s passage into Charleston Harbor – seize the southern end of Morris Island, reduce Battery Wagner by siege, reduce Fort Sumter by siege, then open the harbor to the Navy. The kick off of this campaign, delayed by a day, accomplished its goal of occupying the southern portion of Morris Island.

But that’s where Gillmore called audibles. Some “walk in the park” histories have said Gillmore failed to take Battery Wagner on July 10, setting up failed attempts on July 11 and 18. But consider the sources we have to work with. Gillmore wrote his lengthy account of the campaign after its conclusion. And we can assume some spin worked into that report. But the orders issued during the period of July 10-18 and reports from individuals who were killed or severely wounded were certainly filed before any substantial spin could be imparted.

Brigadier-General George Strong, who lead the initial landings on Morris Island, did not have orders to take Battery Wagner on July 10. And there is little to indicate the assaults of July 11 and 18 were launched to make up for any failure on July 10. Instead the July 11 assault was ordered based on reports that Battery Wagner was weakly held and might have fallen to a strong frontal assault. With more preparation, the assault on July 18 was predicated on the silencing of the Confederate guns in the battery. In other words, something short of a siege, but a little more involved than simple infantry assault.

My take, for what it is worth, is that Gillmore modified the details of the operation to suit the situation he perceived to have in front of him – be that based on good intelligence or not. Aside from questions about the strength of Confederate defenders (both in Wagner and overall around Charleston), good topographical information about Morris Island was only obtained by putting troops on the beach. Erosion and changes to the ship channel forced Gillmore to rethink the approach, particularly how to lay a siege in such constrained space. The assaults of July 11 and 18 were bloody mistakes due to deviations from the original plan. Those deviations were in part due to faulty information, but by the same measure Gillmore’s desire to achieve a short end to the second phase (reduction of Battery Wagner).

Gillmore reacted promptly with another audible within hours of the failed assault of July 18. Before dawn on July 19, orders went forward to convert existing trenches into the first parallel against Battery Wagner. Other instructions came down to prepare the siege batteries for use against Wagner. But before we consider this a realignment back to the original plan to lay siege to Wagner, there was another deviation thrown into the mix. From Gillmore’s official report:

The formidable strength of Fort Wagner, considered with regard to its position, trace, and interior arrangements, as developed in the unsuccessful assault of the 18th of July, induced a modification of the plan of operations, or rather a change in the order previously determined upon…

The demolition of Fort Sumter was the object in view as preliminary to the entrance of the iron-clads. Neither Fort Wagner nor Battery Gregg possessed any special importance as a defense against the passage of the iron-clad fleet. They were simple outposts of Fort Sumter. Fort Wagner was specially designed to prevent the erection of breaching batteries against that work, and was valueless to the enemy if it failed to accomplish that end. To save valuable time, it was determined to attempt the demolition of Sumter from ground already in our possession, so that the iron-clads could entered upon the execution of their part of the programme.

A grain of salt here… regardless of what was done to Fort Sumter, the ironclads would still have to deal with the powerful batteries on Sullivan’s Island. Furthermore, the specter of torpedoes remained in the minds of those afloat. For those reasons, phase four of Gillmore’s plan never played well with Rear-Admiral John Dahlgren in command of the fleet.

OK… another grain of salt here… Gillmore never made any plans to isolate, or blockade, Fort Sumter as was done at Fort Pulaski. As such the reduction of Fort Sumter required the besiegers to inflict catastrophic damage.

Still Gillmore remained oriented on his objectives. The plan now called for two siege operations conducted simultaneously from the same platform. While on the beach side of Morris Island parallels advanced the siege lines forward toward Battery Wagner, breaching batteries would target Fort Sumter. What made this effort technically feasible was the arrival of heavy Parrott Rifles that extended the range of practical siege bombardment nearly five times over that deemed practical before the war.

Over the next few months, I plan to highlight key points in the operations against Battery Wagner and Fort Sumter. But, before we start assuming Gillmore’s plans were finally fixed as the siege lines and batteries went into place, there were more shifts in priority before this operation finally closed!

(Citations from OR, Series I, Volume 28, Part I, Serial 46, page 16.)

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2 responses to “Two sieges for the price of one! Gillmore’s evolving plans on Morris Island

  1. Pingback: “A small artificial island” – Battery Kearny on Morris Island | To the Sound of the Guns

  2. Pingback: 150 Years Ago: A minor little bombardment of Fort Sumter | To the Sound of the Guns

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