XX. Army road and bridge Builders.
“A line of black, which bends and floats
On the rising tide, like a bridge of boats.
If there is one class of men in this country who more than all others should appreciate spacious and well graded highways, or ready means of transit from one section into another, that class is the veterans of the Union Army
; for those among them who “hoofed it” from two to four years in Rebeldom travelled more miles across country in that period than they did on regularly constituted thoroughfares.
Now through the woods, now over the open, then crossing a swamp, or wading a river of varying depth, here tearing away a fence obstructing the march, there filling a ditch with rails to smooth the passage of the artillery,--in fact, “short cuts” were so common and popular that the men endured the obstacles they often presented with the utmost good-nature, knowing that every rood of travel thus saved meant fewer foot-blisters and an earlier arrival in camp.
But there was a portion of the army which could not often indulge in short cuts, which must “find a way or make it,” or have it made for them by others; and as some time and much skill and labor were necessary in laying out and completing such a way in an efficient manner, a body of
men was enlisted for the exclusive purpose of doing this kind of work.
Such a body was the Engineer Corps
, often called the Sappers and Miners
of the army; but so little sapping and mining was done, and that little mainly by the fighting forces, I shall speak of this body of men as Engineers-the name which, I believe, they prefer.
In the Army of the Potomac this corps was composed of the Fifteenth and Fiftieth New York regiments of volunteers and a battalion of regulars comprising three companies.
They started out with McClellan
in the Peninsular Campaign
, and from that time till the close of the war were identified with the movements of this army.
These engineers went armed as infantry for purposes of self-defence only, for fighting was not their legitimate business, nor was it expected of them.
There were emergencies in the history of the army when they were drawn up in line of battle.
Such was the case with a part of them at least at Antietam
, and the Wilderness
, but, so far as I can learn, they were never actively engaged.
The engineers' special duties were to make roads passable for the army by corduroying sloughs, building trestle bridges across small streams, laying pontoon bridges over rivers, and taking up the same, laying out and building fortifica-
tions, and slashing.
Corduroying called at times for a large amount of labor, for Virginia
mud was such a foe to rapid transit that miles upon miles of this sort of road had
to be laid to keep ready communication between different portions of the army.
Where the ground was miry, two stringers were laid longitudinally of the road, and on these the corduroy of logs, averaging, perhaps, four inches in diameter, was laid, and a cover of brush was sometimes spread upon it to prevent mules from thrusting their legs through.
Where the surface was simply muddy, no stringers were used.
It should be said here that by far the greater portion of this variety of work fell to fatigue details from the infantry, as did much more of the labor which came within the scope of the engineers' duties; for the latter could not have accomplished one-fifth of the tasks devolved upon them in time.
In fact, if I except the laying and
A trestle bridge, no. 1.|
taking — up of pontoon bridges, and the laying-out and superintending of the building of forts, there were none of the engineers' duties which were not performed by the fighting force to a large extent.
I state this not in detraction of the engineers, who always did well, but in justice to the infantry, who so often supplemented the many and trying duties of their own department with the accomplishments of the engineer corps.
The quartermaster of the army had a large number of wagons loaded with intrenching tools with which to supply the troops when their services were required as engineers.
The building of trestle bridges called for much labor from the engineers with the Army of the Potomac, for Virginia
gridironed with small streams.
These, bear in mind, the troops could ford easily, but the heavily loaded trains must have bridges to cross on, or each ford would soon have been
A trestle bridge, no. 2.|
choked with mired teams.
Sometimes the bridges built by the natives were still standing, but they had originally been put up for local travel only, not
to endure the tramp and rack of moving armies and their thousands of tons of impedimenta
; wherefore the engineers would take them in hand and strengthen them to the point of present efficiency.
So well was much of this work done that it endures in places to-day as a monument to their thoroughness and fidelity, and a convenience to the natives of those sections.
When a line of works was laid out through woods, much slashing
, or felling of trees, was necessary in its front.
This was especially necessary in front of forts and batteries.
Much of this labor was done by the engineers.
The trees were felled with their tops toward the enemy, leaving stumps about three feet high.
The territory covered by these fallen trees was called the Slashes
, hence Slashing
. No large body of the enemy could safely attempt a passage through such an obstacle.
It was a strong defence for a weak line of works.
The Gabions, being hollow cylinders of wicker-work without bottom, filled with earth, and placed on the earthworks; the Fascines
, being bundles of small sticks bound at both
ends and intermediate points, to aid in raising batteries, filling ditches, etc.; Chevaux-de-frise, a piece of timber
A large Gabion.|
traversed with wooden spikes, used especially as a defence against cavalry; the Abatis
, a row of the large branches of trees, sharpened and laid close together, points outward, with the butts pinned to the ground; the Praise
, a defence of pointed sticks, fastened into the ground at such an incline as to bring the points breast-high ;--all these were fashioned by the engineer corps, in vast
numbers, when the army was besieging Petersburg
But; the crowning work of this
corps, as it always seemed to me, the department of their labor for which, I believe, they will be the longest remembered, was that of pontonbridge laying.
The word ponton
, or pontoon, is borrowed from both the Spanish
languages, which, in turn, derive it from the parent Latin
meaning a bridge, but it has now come to mean a boat
, and the men who build such bridges are called by the French pontoniers
. In fact, the system of ponton bridges in use during the Rebellion
was copied, I believe, almost exactly from the French
The first ponton bridge which I recall in history was built by Xerxes
, nearly twenty-four hundred years ago, across the Hellespont.
It was over four thousand feet long.
A violent storm broke it up, whereupon the Persian “got square” by throwing two pairs of shackles into the sea and ordering his men to give it three hundred strokes of a whip, while he addressed it in imperious language.
Then he ordered all those persons who had been charged with the construction of the bridge to be beheaded.
Immediately afterwards he had two other bridges built, “one for the army to pass over, and the other for the baggage and
beasts of burden.
He appointed workmen more able and expert than the former, who went about it in this manner.
They placed three hundred and sixty vessels across, some of them having three banks of oars and others fifty oars apiece, with their sides turned towards the Euxine (Black) Sea; and on the side that faced the Aegean Sea
they put three hundred and fourteen.
They then cast large anchors into the water on both sides, in order to fix and secure all these vessels against the violence of the winds and the current of the water.
On the east side they left three passages or vacant spaces, between the vessels, that there might be room for small boats to go and come easily, when there was
occasion, to and from the Euxine Sea
After this, upon the land on both sides, they drove large piles into the earth, with huge rings fastened to them, to which were tied six vast cables, which went over each of the two bridges: two of which cables were made of hemp, and four of a sort of reeds called βίβλος
;, which were made use of in those times for the making of cordage.
Those that were made of hemp must have been of an extraordinary strength and thickness since every cubit in length weighed a talent (42 pounds). The cables, laid over the whole extent of the vessels lengthwise, reached from one side to the other of the sea. When this part of the work was finished; quite over the vessels from side to side, and over the cables just described, they laid the trunks of trees cut for that purpose, and planks again over them, fastened and joined together to serve as a kind of floor or solid bottom; all which they covered over with earth, and added rails or battlements on each side that the horses and cattle might not be frightened at seeing the sea in their passage.”
Compare this bridge of Xerxes
with that hereinafter described, and note the points of similarity.
One of the earliest pontons used in the Rebellion
was made of India-rubber.
It was a sort of sack, shaped not unlike a torpedo, which had to be inflated before use. When thus inflated, two of these sacks were placed side by side, and on this buoyant foundation the bridge was laid.
Their extreme lightness was a great advantage in transportation, but for some reason they were not used by the engineers of the Army of the Potomac.
They were used in the western army, however, somewhat.
General F. P. Blair
's division used them in the Vicksburg
campaign of 1863.
Another ponton which was adopted for bridge service may be described as a skeleton boat-frame, over which was stretched a cotton-canvas cover.
This was a great improvement over the tin or copper-covered boat-frames, which had been thoroughly tested and condemned.
It was the variety
used by Sherman
's army almost exclusively.
In starting for Savannah
, he distributed his ponton trains among his four corps, giving to each about nine hundred feet of bridge material.
These pontons were suitably hinged to form a wagon
A canvas pontoon boat.
From a Photograph.|
body, in which was carried the canvas cover, anchor, chains, and a due proportion of other bridge materials.
This kind of bridge was used by the volunteer engineers of the Army of the Potomac.
I recall two such bridges.
One spanned the Rapidan
at Ely's Ford, and was crossed by the Second Corps the night of May 3, 1864, when it entered upon the Wilderness
The other was laid across the Po River
, by the Fiftieth New York Engineers, seven days afterwards, and over this Hancock
's Veterans crossed — those, at least, who survived the battle of that eventful Tuesday-before nightfall.
But all of the long
bridges, notably those crossing the Chickahominy
, the James
, the Appomattox
, which now come to my mind, were supported by wooden
boats of the French
These were thirty-one feet long, two feet six inches deep, five feet four inches wide at the top, and four feet at the bottom.
They tapered so little at the bows and sterns as to be nearly rectangular, and when afloat the gunwales were about horizontal, having little of the curve of the skiff.
The floor timbers of the bridge, known as Balks
, were twenty-five and one-half feet long, and four and one-half
inches square on the end. Five continuous lines of these were laid on the boats two feet ten inches apart.
The flooring of the bridge, called chesses
, consisted of boards having a uniform length of fourteen feet, a width of twelve inches, and a thickness of one and a half inches.
To secure the chesses in place, side-rails
of about the same dimensions as the balks were laid upon them over the outer balks, to which the rails were fastened by cords known as rack-lashings
The distance between the centres of two boats in position is called a bay
. The distance between the boats is thirteen feet ten inches. The distance between the side-rails is eleven feet, this being the width of the roadway.
had to be constructed at either end of a
An angle of Fort Hell (Sedgwick) showing Gabions, Chevaux-de-frise, Abatis and Fraise.
From a Photograph.|
bridge, which was generally done by settling a heavy timber horizontally in the ground, level with the top of the bridge, confining it there by stakes.
A proper approach was then made to this, sometimes by grading, sometimes by corduroying, sometimes by cutting away the bank.
The boats, with all other bridge equipage, were carried upon wagons, which together were known as the Ponton Train
Each wagon was drawn by six mules.
A single boat with its anchor and cable formed the entire load for one team.
The balks were loaded on wagons by themselves, as were also the chesses, and the side-rails on others.
This system facilitated the work of the pontoniers.
In camp, the Ponton Train
was located near army headquarters.
On the march it would naturally be in rear of the army, unless its services were soon to be made use of. If, when the column had halted, we saw this train and its body-guard, the engineers, passing to the front, we at once concluded that there was “one wide river to cross,” and we might as well settle down for a while, cook some coffee, and take a nap.
In order to get a better idea of ponton-bridge laying, let us follow such a train to the river and note the various steps in the operation.
If the enemy is not holding the opposite bank, the wagons are driven as near as practicable to the brink of the water, unloaded, and driven off out of the way. To avoid confusion and expedite the work, the corps is divided up into the abutment, boat, balk, lashing, chess, and side-rail parties.
Each man, therefore, knows just what he has to do. The abutment party takes the initiative, by laying the abutment, and preparing the approaches as already described.
Sometimes, when the shore was quite marshy, trestle work or a crib of logs was necessary in completing this duty, but, as the army rarely approached a river except over a recognized thoroughfare, such work was the exception.
While this party has been vigorously prosecuting its special labors, the boat party
, six in number, have got a ponton afloat, manned it, and ridden to a point a proper distance above the line of the proposed bridge, dropped anchor, and, paying out cable, drop down alongside the abutment, and go ashore.
The balk party
are on hand with five balks, two men to each, and having placed these so that one end projects six inches beyond the outer gunwale of
the boat, they make way for the lashing party
, who lash them in place at proper intervals as indicated on the gunwales.
The boat is then pushed into the stream the length of the balks, the hither ends of which are at once made fast to the abutment.
The chess party
now step to the front and cover the balks with flooring to within one foot of the ponton.
Meanwhile the boat-party has launched another ponton,
A wooden pontoon boat.
From a Photograph.|
dropped anchor in the proper place, and brought it alongside the first; the balk party, also ready with another bay of balks, lay them for the lashing party to make fast; the boat being then pushed off broadside — to as before, and the free end of the balks lashed so as to project six inches over the shore
gunwale of the first boat.
By this plan it may be seen that each balk and bay of balks completely spans two pontons.
This gives the bridge a firm foundation.
The chess party continue their operations, as before, to within a foot of the second boat.
And now, when the third bay of the bridge is begun, the side-rail
party appears, placing their rails on the chesses over the outside balks, to which they firmly lash them, the chesses being so constructed that the lashings pass between them for this purpose.
The foregoing operations are repeated bay after bay till the bridge reaches the farther shore, when the building of
another abutment and its approaches completes the main part of the work.
It then remains to scatter the roadway of the bridge with a light covering of hay, or straw, or sand, to protect it from wear, and, perhaps, some straightening here and tightening there may be necessary, but the work is now done, and all of the personnel
may cross with perfect safety.
No rapid movements are allowed, however, and man and beast must pass over at a walk.
A guard of the engineers is posted at the abutment, ordering “Route step!”
as the troops strike the bridge, and sentries, at intervals, repeat the caution further along.
By keeping the cadence in crossing, the troops would subject the bridge to a much greater strain, and settle it deeper in the water.
It was shown over and over again that nothing so tried the bridge as a column of infantry.
The current idea is that the artillery and the trains must have given it the severest test which was not the case.
In taking up a bridge, the order adopted was the reverse of that followed in laying it, beginning with the end next the enemy, and carrying the chess and balks back to the other shore by hand.
The work was sometimes accelerated by weighing all anchors, and detaching the bridge from the further abutment, allow it to swing bodily around to the hither shore to be dismantled.
One instance is remembered when this manoeuvre was executed with exceeding despatch.
It was after the army had recrossed the Rappahannock
, following the battle of Chancellorsville
So nervous were the engineers lest the enemy should come upon them at their labors they did not even wait to pull up anchors, but cut every cable and cast loose, glad enough to see their flotilla on the retreat after the army, and more delighted still not to be attacked by the enemy during the operation, -so says one of their number.
One writer on the war speaks of the engineers as grasping “not the musket but the hammer
,” a misleading remark, for not a nail is driven into the bridge at any point,
When the Army of the Potomac retreated from before Richmond
in 1862 it crossed the lower Chickahominy
on a bridge of boats and rafts 1980 feet long.
This was constructed by three separate working parties, employed at the same time, one engaged at each end and one in the centre.
It was the longest bridge built in the war, of which I have any knowledge, save one, and that the bridge built across the James
, below Wilcox's Landing, in 1864.
This latter was a remarkable achievement in ponton engineering.
It was over two thousand feet long, and the channel boats were firmly anchored in thirteen fathoms of water.
The engineers began it during the forenoon of June 14, and completed the task at midnight. It was built under the direction of General Benham
for the passage of the wagontrains and a part of the troops, while the rest crossed in steamers and ferry-boats.
But ponton bridges were not always laid without opposition or interference from the enemy.
Perhaps they made the most stubborn contest to prevent the laying of the bridges across the Rappahannock
in December, 1862.
The pontoniers had partially laid one bridge before daylight, but when dawn appeared the enemy's sharpshooters, who had been posted in buildings on the opposite bank, opened so destructive a fire upon them that they were compelled to desist, and two subsequent attempts to continue the work, though desperately made, were likewise brought to naught by the deadly fire of Mississippi rifles.
At last three regiments, the Seventh Michigan, and the Nineteenth and Twentieth Massachusetts, volunteered to cross the river, and drive the enemy out of cover, which they did most gallantly, though not without considerable loss.
They crossed the river in ponton boats, charged up the steep bank opposite, drove out, or captured the Rebels
holding the buildings, and in a short time the first ponton bridge was completed.
Others were laid near by soon after.
I think the engineers lost more men here-I mean now in actual combat — than in all their previous and subsequent service combined.
Ponton bridges were a source of great satisfaction to the soldiers.
They were perfect marvels of stability and steadiness.
No swaying motion was visible.
To one passing across with a column of troops or wagons no
motion was discernible.
It seemed as safe and secure as mother earth, and the army walked them with the same serene confidence as if they were.
I remember one night while my company was crossing the Appomattox
on the bridge laid at Point of Rocks
that D. Webster Atkinson
, a cannoneer, who stood about six feet and a quarter in boots-dear fellow, he was afterwards mortally wounded at Hatcher's Run
,--being well-nigh asleep from the fatigue of the all-night march we were undergoing, walked off the bridge.
Fortunately for him, he
Poplar Grove Church.|
stepped — not into four or five fathoms of water, buta ponton.
As can readily be imagined, an unexpected step down of two feet and a half was quite an “eyeopener”
to him, but, barring a little lameness, he suffered no harm.
The engineers, as a whole, led an enjoyable life of it in the service.
Their labors were quite fatiguing while they lasted, it is true, but they were a privileged class when compared with the infantry.
But they did well all that was required of them, and there was no finer body of men in the service.
The winter-quarters of the engineers were, perhaps, the most unique of any in the army.
In erecting them they gave their mechanical skill full play.
Some of their officers' quarters were marvels of rustic design.
The houses of one regiment in the winter of ‘63-4 were fashioned out of the straight cedar, which, being undressed, gave the settlement a quaint but attractive and comfortable appearance.
Their streets were corduroyed, and they even boasted sidewalks of similar construction.
Poplar Grove Church, erected by the Fiftieth New York Engineers, a few miles below Petersburg
, in 1864, still stands, a monument to their skill in rustic design.