Category Archives: Engineers

Fortification Friday: The symbiotic relationship between attack and defense

As we leaf through Mahan’s Treatise on Field Fortifications, the lesson plan offered, after defining components of the profile and trace, an important perspective for planning and evaluating fortifications – a connection between the attack and defense of the works:

The attack and defense of intrenchements bear a necessary relation to each other; and it is upon a knowledge of the course pursued by the assailant, that the principles regulating the defense should be founded.

Grant me some license for an analogy here and call this a symbiotic relationship.  Symbiotic, that is, borrowed from biology and defining two organisms of different species that exhibit a long-term, close interaction.  In the case of military affairs, the only reason a place would be defended with earthworks is because the defender feels an attacker might wish to gain possession.  Furthermore, the defender would build the works specifically to counter (if not deter) the most likely form of attack.  Likewise, the attacker would plan the assault based on knowledge of the layout of the defenses.  In short, one plan will exist only because of the other, counter, plan.  Otherwise, there’s simply no reason for the planned action – be that placing a defensive work or organizing an assault of the position.

Mahan elaborated further, providing the students a generalized example of what an attack looked like:

 An attack is, generally, opened by a fire of the enemy’s artillery, whose objective is to silence the fire of the intenchments, and to drive the assailed from the parapet; when this object is attained, a storming party, which usually consists of a detachment of engineer troops, a column of attack, and a reserve, is sent forward, under the fire of the artillery, to the assault. The detachment of engineer troops proceeds the column of attack, and removes all obstacles that obstruct its passage into the ditch. The line of march is directed upon a salient, through a sector without fire, and on the prolongation of the capital, as this line is least exposed to the fire of the works.

Depicting that approach on Mahan’s figure:


See how this approach was designed to take advantage of an inherent flaw of the works? Mahan continued with more exploitation of the fortification flaws:

When the ditch is gained, the party makes its way to a re-entering angle, where, sheltered from the fire of the flanks, the work is entered by the column of attack, either by making a breach in the parapet, or else by means of ladders.  The reserve supports the column of attack in case of need; and if it is driven from the works, covers its retreat.

Again, as that would look on Mahan’s figure:


This approach allowed the attacker to pick apart the defense by working under the parapet within the ditch inside the dead space, avoiding the angles of defense.

So how does that look from the defenders side?

The manner of making the defense is with artillery, musketry, the bayonet, and sorties.  The enemy is attained at a distance by the fire of the artillery and musketry, whose effect will chiefly depend upon the length of time that he is kept exposed to it by the ditch, and the obstacles in front of it. The bayonet is resorted to, as soon as the enemy shows himself on the berm; and sorties are made, either when any irresolution or confusion is seen in the enemy’s ranks, or at the moment he is repulsed from the parapet.

Note that Mahan didn’t emphasize here the nature of the parapets, faces, and flanks in order to build the perfect defensive line.  That technical perspective he saved for a more detailed explanation.  Instead he focused on what the defender could do with their weapons.  Implied in the notion of the sortie is that the defender retained high motivation to conduct such a counter-attack.  And with that, Mahan is admitting that flaws would be present in any defense.  To mitigate those flaws, where existing, the defender applied cold steel, hot lead, flesh, and bone.

But you see here how the nature of attack and defense fit against each other.  The attack had to be planned with a mind to exploit the flaws of the defense.  The defense had to be planned to minimize those flaws.  After establishing that symbiotic relationship, Mahan proceeded to lay out nine principles of the defense – some technical, others tactical, and yet others addressing the “spirit” of the defenders.  We’ll take a look at those next week.

(Citations from Dennis Hart Mahan, A Treatise on Field Fortifications, New York: John Wiley, 1852, pages 5-6.)

Fortification Friday: Know your banquettes and slopes

Over the last couple of posts in this series, I’ve discussed parapets and their function.  Now let us turn to the parts of a parapet and look at those in detail.  As a refresher, this is Mahan’s profile of the parapet (highlighted line):


Mahan defined this profile as the lines between points A-B-C-D-E-F.   It’s important to note that each individual line (defined between the points) also defines a separate component of the parapet.

Between points A and B is the Banquette Slope:


Specifically, point A is the Foot of the Banquette Slope and B is the Crest of the Banquette Slope.

Wait… what is a Banquette?  Mahan described the Banquette as:

The banquette is a small terrace on which the soldier stands to deliver his fire ; the top of it is denominated the tread, and the inclined plane by which it is ascended the slope.

So this explains lines A-B and B-C.  The latter being the Tread of the Banquette, and including point C, the Foot of the Interior Slope:


From a functional standpoint, the Banquette had to be wide enough to allow a rank or ranks of soldiers to stand in formation and work their musket.  The measure would be different depending on the number of ranks that the defender planned to use.  One rank might get by with two feet of width.  Two ranks required four feet.  So something on the order of 4 ½ to 5 feet would be preferred to allow ease of movement.  The Banquette was also given a slight slope to the interior to allow for drainage.

The Slope of the Banquette (A-B) was structured as the hypotenuse of a right triangle.  The slope would be a compromise providing support for the Tread while offering the lowest slope for the troops to climb.

One other functional requirement to consider about the Banquette is its height above the tere-plein (natural surface level), or interior, and the height of the parapet.  The troops had to be able to stand on the Banquette and shoot with most of their body protected by the other parts of the Parapet.  This governed the overall height of the Parapet somewhat, given average height of soldiers and such.

Moving further down the profile of the Parapet, we come to the Slope portion of the Parapet.  By adding point D, the Interior Crest, we have line C-D, known as the Interior Slope:


As with the height of the Tread, this line’s length was governed by the need to allow soldiers to fire over the Parapet.  A sharp incline of this line allowed the troops space to move while keeping the mass close to their bodies.  But not being the most efficient structural support angle, that incline required careful maintenance.

Line D-E, with E being the Exterior Crest, is called the Superior Slope:


The Superior Slope declined outward (towards point E).  This allowed soldiers to depress their weapons to engage targets directly in front of the works.  This also ensure any fires hitting the front of the fort would glance upward and away from the defenders (hopefully).  The angle of the Superior Slope was also a compromise.  Too shallow and the Parapet might be excessive and perhaps not allow enough declination for the muskets.  Too deep and the Parapet’s strength is compromised.

Continuing the same convention, the Exterior Slope is line E-F, where point F is the Foot of the Exterior Slope:


This portion of the Parapet had the important mission of stopping projectiles.  The preferred angle was 45º, or the natural slope at which loose dirt will pile.  Structurally, that was the best support angle for the Parapet.  Furthermore, when under fire, any dirt thrown up from the Exterior Slope would naturally fall back to that angle… one would expect.

The Exterior Slope completed the profile of the Parapet.  But there is one other part to consider, although it is not part of the defined parapet – line F-G:


Point G is the crest of the Scarp, part of the Ditch.  Mahan called this the Berm.  The Berm connected the Parapet to the Ditch.

I have a problem with the choice of words here.  In modern context, berm is often a raised mound, almost a Parapet itself.  We spoke of “crossing the berm” in the Gulf Wars as noting a passage through defensive works thrown up in the desert.  Likewise, berms are tall, lengthy mounds built between roads and subdivisions to block noise.  And let’s not forget berms put up in front of raising flood waters.  So you see, a “berm” means some other shape to most modern readers.

But for Mahan, the Berm was a construct that allowed the weight of the Parapet to stand on something other than the back edge of the ditch (the Scarp, which we will discuss later).  Frankly, he wrote:

The berm is a defect in field works, because it yields the enemy a foot-hold to breathe a moment before attempting to ascend the exterior slope. It is useful in the construction of the work for the workmen to stand on; and it throws the weight of the parapet back from the scarp, which might be crushed out by this pressure. In firm soils, the berm may be only from eighteen inches to two feet wide; in other cases, as in marshy soils, it may require a width of six feet. In all cases, it should be six feet below the exterior crest, to prevent the enemy, should he form on it, from firing on the troops on the banquette.

Thus the Berm was a necessary evil.  It was a risk that need mitigation during construction.

These terms become very important when considering the engineering involved to build a fort.  Each component had a function. Those functions determined the measures of the line.  Engineers, being engineers, would compute those measures based on formulas provided by Mahan and others.  In short, the troops didn’t just throw this sort of thing up randomly:

They ENGINEERED it.  And that engineering involved careful study of the task using some of those terms presented above.

(Citations from Dennis Hart Mahan, A Treatise on Field Fortifications, New York: John Wiley, 1852, pages 1-3, 22.)

“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.”


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:


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.


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:


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.)


“With the greatest exertion…”: Engineers complete the approaches for the James River crossing

Picking up from yesterday’s post, let us turn again to the report of Brigadier-General Godfrey Weitzel, Chief Engineer, Army of the James, in regard to preparations made to cross the Army of the Potomac, 150 years ago.  For June 13, Weitzel indicated that his capable subordinate, Lieutenant Peter Michie, was at Fort Powhatan and engaged:

June 13, without waiting for a reply, I directed Lieutenant Michie to proceed to the place and prepare the timber necessary for the corduroy across the marsh, as it seemed probable that it would be wanted. With 150 axmen, 1,200 feet of timber, in sticks averaging 6 inches in diameter and 20 feet long, was cut and prepared before dark, and over 3,000 feet was brought down to the creek above Fort Powhatan ready to be rafted across.

For reference, again here’s the map provided from Weitzel’s report:


Later that afternoon, Weitzel received conformation as to the location. He had anticipated correctly:

At about 3 p.m. I received a dispatch from General Grant informing me that the head of his column would be at the bridge-head at 10 a.m. the next day, and directing me to build approaches to the bridge at once at the point designated. An officer was immediately dispatched to Lieutenant Michie, with instructions to begin at once, using the detail that he had with him, and that I would join him as soon as possible with a heavy detail to carry on the work. With the greatest exertion on the part of both officers and men the approaches on both sides of the river, with a pier 150 feet long over the soft marsh on the east bank, was completed at 9.45 a.m., a quarter of an hour before the time indicated by General Grant; and the bridge would have been built, ready for the passage of the troops, at or before 10 a.m. on the 14th if the pontoon train had arrived, as it should, at this time….

There are several moving parts to this operation.  Not the least of which is the engineers bringing up the bridges.  And that was the problem:

Through inexcusable tardiness, and more than culpable neglect of duty, Captain [James L.] Robbins, of the Fiftieth New York Volunteer Engineers, did not appear in sight with his pontoons until after 12 o’clock at noon on the 14th, although he had but eighty miles to come from Fort Monroe, and received his orders to go as fast as he could at 2 p.m. on the 13th.

Robbins was part of the Engineer Brigade operating directly with Brigadier-General Henry Benham out of Fort Monroe at that time.  Weitzel soon found Captain Robbins:

So anxious was I that there should be no delay that I sent a dispatch boat to look for the pontoons down the river, with orders to go until  they were found and hurry them up. Fifteen miles below Jamestown Island they were found at anchor, the captain being asleep.

In addition to the preparations mentioned above, Weitzel or Michie (or both) had six schooners – three each above and below the bridge site – setup as anchor points for the intended bridges.

While Weitzel and Michie completed work facilitating the crossing, north of the James River, the 50th New York Engineers (minus of course Robbins and his tardy pontoon bridge), were busy preparing the roads that would get the Army of the Potomac to crossing points.

(Citations from OR, Series I, Volume 36, Part III, pages 754-5; Volume 40, Part I, page 676-7.)


Thirty-eight bridges, aggregate length 6,458 feet: The 50th NY Engineers on the Overland Campaign

Lieutenant-General U.S. Grant’s concept for the Overland Campaign depended upon out-maneuvering the Army of Northern Virginia.  The problem facing the Army of the Potomac in that regard was the same which confronted Federal forces in 1861 … and 1862… and 1863… a lot of rivers to cross.  One can drag a finger across the map to indicate a line of advance simple enough. But when the troops start marching that line out, they come to an abrupt halt at the first good sized watercourse.  If maneuver is the game, then a commander must have a few bridges in his back pocket.

In the spring of 1864, Major-General George G. Meade had more than a few bridges in his back pocket.  Those bridges were the charge of Lieutenant-Colonel Ira Spaulding and his men of the 50th New York Engineers.  For the campaign, Spaulding organized the regiment into four battalions, all built around sets of bridges:

  • First Battalion – Major Wesley Brainerd, with Companies B, F, and G, had one fourteen boat French pontoon bridge.  First Battalion also supported the Second Corps.
  • Second Battalion – Major Edmund O. Beers, with Companies E, H, and L, had one thirteen boat French pontoon bridge (part of which you are familiar with).  This battalion supported Sixth Corps.
  • Third Battalion – Captain James H. McDonald (and later Major George W. Ford), with Companies D, K, and M, had a thirteen boat French pontoon bridge.  Third Battalion supported Fifth Corps.
  • Reserve Battalion – Under Spaulding’s direct command with Companies C and I.  This battalion had two pontoon trains with twelve canvas boats each.  Captains William Folwell and Martin Van Brocklin commanded one of these apiece. The reserve also had two wing trestles.

In addition to he bridges, each of the three numbered battalions carried the entrenching tools for their supported corps.

From the very start of the campaign, the army used these bridges.  In fact, before leaving Culpeper, the engineers put in a span over the Rappahannock River at Kelly’s Ford in order to facilitate the start of the march south.  As the campaign progressed, the engineers bridged the Rappahannock, Rapidan, Po, and North Anna.

A good photographic study of the crossing of that latter river at Jericho Mills exists in the Library of Congress collection:

Notice those are the canvas boats of the Reserve Battalion.

On May 27, the 50th Engineers began spanning another river, a bit closer to Richmond and perhaps familiar to the veterans – the Pamunkey.  And the crossing there was a “contested” crossing:

May 27, the Reserve Battalion, with two canvas pontoon trains, accompanying General Sheridan’s command, reached the Pamunkey at Hanovertown about daylight. Captain Van Brocklin having the advance put a couple of boats together about a mile from the river, carried them to the river on the men’s shoulders, and sent over dismounted cavalry in these boats to drive away the enemy’s pickets. This was done after a slight skirmish, and Captain Van Brocklin immediately commenced constructing his bridge, completing it in about one hour, assisted by Captain Folwell and a portion of his company; length of bridge, 180 feet. General Torbert’s division of cavalry immediately commenced crossing on this bridge.

That’s how you cross a river under fire and force a bridgehead!  Later that day, a second canvas bridge went over Pamunkey just above the first.

With the cavalry across, the engineers needed to increase the number of crossing points to move the infantry over.  But the problem at that time was most of the wood pontoon bridges were just leaving the water on the North Anna that morning.  Getting those bridges down to the Pamunkey would at best be just in time to be too late.  So Spaulding’s engineers made do with what they had, using part of the other canvas bridges:

May 28, Captain Folwell reached Mrs. Nelson’s crossing at 6 a.m., and at 7. a.m. had a canvas bridge completed across the Pamunkey at this point of 146 feet in length. Owing to the scarcity of material this bridge was built in long spans of 21 feet, the balks alternating on the gunwales, and over this seemingly frail bridge passed without accident two divisions of the Sixth Corps with their artillery.

First Battalion arrived that morning and proceeded to Nelson’s Crossing to lay the first of the wooden bridges over the river at that point.  Second battalion arrived in the afternoon and Beers directed work laying another bridge.  Before the day was done, the engineers added another wooden pontoon bridge at the Hanovertown crossing.  And in addition they placed a canvas bridge over Mattapony Creek, for a total of five placed on May 28.

Grant, Meade, and the Army of the Potomac had “bounced” the Pamunkey.  More fighting lay ahead, and more rivers to cross.  In his report covering the spring campaign, Spaulding included a table listing all the bridges built north of the James River:


Thirty-eight bridges to a total length of 6,458 feet.  And that is not counting the most important bridge of the campaign – 2,200 feet across the James. Summarizing the performance, Spaulding wrote:

…I believe the pontoon trains have been promptly on time when ordered, the bridges rapidly and skillfully built, and all other engineering operations of this command faithfully performed. Whatever credit may be awarded for this is mainly due to the energy and skill of the officers in immediate charge of the several works and to the zealous and faithful co-operation of the men under their command.

Those bridges allowed the army to reach places like the Wilderness, Spotsylvania, North Anna, Totopotomy, Cold Harbor, Petersburg, and eventually Richmond and Appomattox. Though they might not have charged any works, the men of the 50th New York Engineers were every part of that victory.

(Citations from the first half of Spaulding’s report on the Overland Campaign, OR, Series I, Volume 36, Part I, Serial 67, pages 304-316.)