Category Archives: Engineers

“I decidedly prefer the rope mantlets.”: Hunt and Abbot prepare for a siege

Yesterday, I made short reference to Colonel Henry L. Abbot’s suggestion to Brigadier-General Henry Hunt in regard to mantlets for the siege train at Petersburg.  To properly set this part of the story, let me step back to June 14, 1864 and a response from Major-General Delafield, the Army’s Chief Engineer (“Army” as in “all the Army” sense), to Brigadier-General John G. Barnard, Chief Engineer, Army of the Potomac.  The correspondence involved materials forwarded from Washington to Fort Monroe.  And one of the items discussed was mantlets:

Some further information is desired as to the armament for which these mantlets are intended. They were originally adopted for embrasures cut down into a parapet to suit guns mounted on ship truck carriages, which left a large opening to be covered over the gun. Now, in our siege batteries from the top of the 32-pounder, when in battery, to the crest of the parapet is only one foot nine inches to be covered by the mantlet, and with the siege 4½-inch ordnance gun, one foot four inches. This small space over the gun closed by rope gives but very little strength, in addition to which the rope is not musket or rifle proof at 200 yards. These considerations induced me to send you at Yorktown in 1862 wood and boiler-iron mantlets, with a box of chisels to cut the iron to suit your guns. A part of these old ones have lately been found by Stewart at Suffolk and sent forward; that may suffice for some fifty or sixty guns, giving me time to learn your wishes in regard to others to be forwarded and to learn the size of the guns. If made of rope you cannot alter them to suit guns of different exterior diameters, but it made of wood and iron you can enlarge the opening at pleasure. The splinters from the wood and iron are objectionable produced by artillery. During such a fire they would probably be withdrawn and used to guard against infantry fire only. While the rope would not give splinters, yet at the same time would not be proof against the rifle musket-balls. Advise me from Old Point by telegram; say “rope” or “iron and wood” and I will understand you. Also give diameters of guns, exterior.

To answer this question, Barnard turned to Hunt.  And Hunt consulted Abbot.

First off, you might ask what are mantlets?  Well let us start with what an embrasure is – “an opening made in the parapet for a gun to fire through.”

embrasure

The definition and illustration come from John Tidball’s 1891 Manual of Heavy Artillery.  Looking at Figure 4 – the right side and upper center – we see the cut through the parapet allowing the muzzle of the cannon an unobstructed line to fire out.  And we see Tidball offered views of direct, oblique, and high angle embrasures.  But, there are two tactical problems here.  First is maintenance.  The force and shock of firing would in time erode and enlarge the opening.  Since the embrasure faced the enemy, simply spading more dirt into place was not practical.  So common practice was to place raw-hide, gabions, or other reinforcement around the embrasure.  Tidball preferred iron plates to form a lining of the embrasure, as depicted in Figure 5 (to the left).

But that leaves us with the other problem – if the gun could fire out, the enemy could fire in!  In Figure 5, Tidball demonstrated the use of an iron plate as a mantlet, which he defined as “a shield placed over the mouth of an embrasure to prevent musketry bullets and fragments of shells from flying through and injuring those serving the piece.” (And recall the batteries on Morris Island used similar iron linings and mantlets, formed from the boilers of the blockade runner Ruby in 1863.) A door in the center, roughly a foot high and six inches wide, allowed the crew to pass a rammer through when loading, sight down the piece, and project the muzzle.  The preference was to make that opening as small as practical, still allowing for the service of the piece.

As alluded by Delafield, iron was not the only material that could serve as a mantlet.  Wood and iron, though resistant to blast damage and musket fire, had the disadvantage of producing splinters.  Rope, as Delafield stated, didn’t have the splinter problem, but was not considered stiff enough to resist musketry.  But what Delafield apparently didn’t take into account were experiments by Abbot to devise a better rope mantlet, as he advised Barnard about responding to Delafield:

I decidedly prefer the rope mantlets. I find by trial at twenty paces that the penetration of our Springfield rifle, elongated bullet, is between two and two and five-tenths inches. The mantlets are six inches thick and they are thus perfectly rifle-proof. Their dimensions are the following, which are very convenient in practice:

Abbot_Mantlet1

The opening can readily be cut larger if necessary. We have done so at least in one instance, to enlarge the traverse of the gun in an oblique embrasure. The men are afraid of splinters from a cannon-ball-and I think justly so–with the wood and iron mantlets. Moreover, the blast of a light 12-pounder has already rendered unserviceable one of the iron mantlets of this pattern.

Abbot_Mantlet2

I therefore entirely agree with yourself and General Hunt in thinking that only rope should be ordered. I think the dimensions cannot be improved. As to number required, my train proper, which is entirely distinct from my present guns, consists of forty-six guns requiring mantlets, and ten 8-inch siege howitzers which I think can hardly be used with them. I have here seventeen rope mantlets and twenty-three wood and iron, one of the latter unserviceable. As they are very liable to be destroyed, and moreover are quite useful even for light guns when sharpshooters are as troublesome as they have been here at times (I have had two men killed besides some wounded in my own regiment by them already), I think that about 100 could be safely ordered (besides those I have on hand). They should be made of tarred rope, like the old ones.

So with a thicker set of ropes, the gunners were better protected.

Turning back to Tidball’s post-war manual, he offered two illustrations of rope mantlets:

mantlets

Figure 2 above matches somewhat to the second illustration offered by Abbot in 1864.  The use of rope afforded some flexibility for those working at the muzzle with rammers and sponges. Tidball stated those mantlets weighed 400 pounds.  Figure 3 appears to be a more refined fitting, which I would question in regard to ease servicing the weapon.

Without mantlets, sharpshooters could reduce the efficiency of the guns, if not silence them completely.  Thus these relatively minor devices became rather important as the army transitioned into siege operations.  In fact, I dare say any work discussing the fortifications at Petersburg, at a tactical level, should include a proper discussion of mantlets… lest the author be accused of dealing with the subject lightly.

(Citations from OR, Series I, Volume 40, Part II, Serial 81, pages 21, 223-4;  John C. Tidball, Manual of Heavy Artillery Service: For the Use of the Army and Militia of the United States, Washington, D.C.: James J. Chapman, 1891, pages 385-6, 399, and Plates 61 and 68.)

Crossing the Pontoons: Forbes recalls his crossing of the James

Edwin Forbes was among the best known illustrators of the Civil War.  Working for Frank Leslie’s Magazine, Forbes produced some vivid drawings depicting the action… and inaction… of life with the armies.  Forbes also provided a great narrative of his wartime experiences in Thirty Years After: An Artist’s Memoir of the Civil War.  Here’s his account of crossing the James River, 150 years ago:

A most interesting movement in my army experience was the crossing of the James River during the advance of the Army of the Potomac on Petersburg. The longest pontoon bridge that was build during the war was here made use of, and was crossed by the left wing of the army, while the right wing made use of steamboats further up the river near City Point.

I took position near the head of the bridge, and watched the column in its course. Regiments of infantry came surging along at route step, ragged and footsore, their faces much discolored with powder-stain and dust.  Officers were scarcely discernible from privates.  The latter were laden with all kinds of traps and plunder, and the pack mules and horses had more than the usual burden.  Everything bore the terrible imprint of a month’s hard fighting, and made sad contrast to the hopeful men who in new uniforms had so recently started out from the winter camp near Culpepper, under the great commander, Grant.  The forces had been terribly reduced in numbers, but with the same determined spirit that always pervaded the troops, even in defeat, the column marched promptly and cheerfully forward. Out from the shore was a fleet of war vessels to protect the bridge, and upon one of them was a group of newly and jauntily dressed sailors, who had evidently experienced no hard service. With open-eyed wonder they watched the progress of the column, and laughed loudly at the grotesqueness that misfortune had given to many groups of soldiers. There was indeed great contrast in the two arms of the service, but my heart went out in sympathy to the poor fellows with tattered clothing and blackened faces. All day the throng poured over the bridge, and with each moment came changing scenes. This was heightened by the many steamboats and sailing crafts anchored in the river, and on the steep bluff of the farther bank arose Fort Powhatan, an abandoned earthwork, which had been thrown up by the Rebs to dispute the ascent of the stream.  Low muttering like distant thunder was after a time heard from the southwest; the advance had arrived at Petersburg.

But before long the sun sank into the rest, and evening brought a beautiful picture. Hundreds of bright camp fires on the river bank lit up the bridge, which, with the colored lights flung out from the vessels, looked like fairyland. The trains clattered noisily along, and the many sounds of a moving army rose in the still night air, and were accompanied by the boom of distant cannon – that solemn suggestion of deadly conflict. Long into the night I watched this moving panorama, until from sheer exhaustion I sought repose.

One view of the crossing of the James, 150 years ago.

(Citation from Forbes, Edwin. Thirty Years After: An Artist’s Memoir of the Civil War. Baton Rouge: Louisiana State UP, 1993, pages 189-90.)

 

Build a bridge – immediately – at Fort Powhatan: A busy day for Henry Benham

At some point in the future, I wish to examine the 1864 crossing of the James River to the level of detail offered for the 1863 crossing at Edwards Ferry.  There were numerous moving parts to the operation.  Each of which adds color to an important story.  As in June 1863, the Army of the Potomac didn’t just skip over a river.  And just as with the crossing at Edwards Ferry, the crossing opened a path leading to – in the case of the James River crossing, ten months later – victory.  (And a quick plug here, Brett has compiled many resources pertaining to the 1864 crossing on Beyond the Crater.)

Just as with the 1863 crossing, a central player in the effort to cross the James was Brigadier-General Henry Benham.  Readers may recall a lot of friction between Benham and army headquarters during the June 1863 crossing.  And one has the perception that Benham left the bridge building details to his subordinates (capable subordinates, I would add).  A similar situation existed in June 1864.  Except, however, Benham was getting order from multiple directions… though all flowing down from Lieutenant-General U.S. Grant.

For Benham, June 14, 1864 began at 5:15 a.m. when he received an order from Army of the Potomac Headquarters, sent out the previous evening:

The major-general commanding directs that all pontoons and other bridge materials in your possession be brought immediately to Fort Powhatan.

At this time, Benham was still quartered at Fort Monroe, managing the materials shifted south from Washington in support of the campaign.  He had already forwarded on pontoon train, by boat, up the James River, under Captain James Robbins the previous day.  And as mentioned yesterday, Robbins was late.  Now on the morning of June 14, the pontoons were not at the crossing site.  And Benham was miles away, apparently out of touch.

At 10:45 a.m. Major-General Andrew A. Humphreys, Chief of Staff, Army of the Potomac, again messaged Benham:

The commanding general directs that immediately upon the receipt of this communication you bring all the bridge material you have, or that may be at Old Point Comfort, to Powhatan with all the expedition possible, and report its arrival.  Similar orders were sent you last night, telegraphed through the White House.

And… because Humphreys was watching this task as a good Chief of Staff should, he sent another message at 11:15 a.m., with more instructions:

The commanding general directs that immediately upon the arrival of the bridge material at Fort Powhatan you construct the bridge across the James River at the point selected by General Weitzel, and the approaches to which are now being prepared.

And we think cell phones, text messages, and emails are bad today!

Benham didn’t respond to the first message until just before 11 a.m., and likely had not received the 10:45 or 11:15 a.m. message.  He told Humphreys:

Yours received at 5.15 a.m. to-day.  I sent pontoon bridging according to orders yesterday, as advised you at 9 a.m. At 10.15 to-day I received orders from General Butler to send them and go up myself. Presuming that these must be by authority of General Grant, I am now starting at 11, and will communicate with you as soon as possible.

Benham followed this up with another message to headquarters at 4 p.m., while  on the steamer J.A. Warner, near Wilson’s Landing.  He acknowledged receipt of the 11:15 a.m. orders, but had left Fort Monroe, as indicated, by 11 a.m.  Now the question arose, “is the bridge complete?”  At 9:30 p.m. Major-General George Meade sent that inquiry directly to Benham:

What progress in throwing the bridge, and at what time can you complete it, so far as you can now tell?  I desire the work to be continued all night, if practicable.

Benham responded:

The bridge has now the last boat in position and the raft is ready to close the gap completely whenever it is safe to do so with reference to the boats below, about which I am greatly in doubt. The bridge can be completed in fifteen minutes if you so order it.  If it is important for the troops here to cross at once it can be done by closing the gap and holding the troop steamers and quartermaster’ boats below and let them pass in a body afterward, if you so order it.

Keep in mind, what Benham described here is an opening in the middle of the bridge, with a set of pontoons pulled out of line, to allow passage of ships upriver.  The engineers built the bridge with that in mind, so as to allow steamers to support crossing of infantry and equipment at other points along the river.  Unlike the June 1863 crossing, the Army of the Potomac could call upon watercraft to effect the movement.  Already at this time portions of Major-General Winfield S. Hancock’s Second Corps were crossing by boat.  But with no means of loading wagons or artillery on boats, the bridges were still vital to the movement.Meade’s response came at 11:30 p.m. (received by Benham at 12:45 the next morning):

Complete the bridge. General Burnside, with the Ninth Corps, will be ordered to cross at once. Request, in my name, the officer in command of the Atlanta to stop all boats below the bridge, and to-morrow a time will be fixed and a selection made of such as it is important to pass through. Take charge of the bridge. General Burnside will be directed to refer to you in passing over his command. Acknowledge receipt.

But… Meade would audible yet another change within minutes of that order:

I have changed the orders, and now have directed Burnside, Wright, and Warren to send over their trains and surplus artillery with guards.  I don’t like to cross any troops till the big train gets nearer to us.

With that, those at the bridge stood ready to support the crossing.  Of note, Meade mentions the USS AtlantaThere she was, former Confederate ram, now employed to keep the Confederate ironclads bottled up in the James River.  An interesting side note, if you will, with respect to the naval support for the Overland Campaign.(Citations from OR, Series I, Volume 40, Part II, Serial 81, pages 4, 22-4.)