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Henry Wager Halleck.

Elements of Military Art and Science Or, Course Of Instruction In Strategy, Fortification, Tactics Of Battles, &C.; Embracing The Duties Of Staff, Infantry, Cavalry, Artillery, And Engineers; Adapted online

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Online LibraryHenry Wager HalleckElements of Military Art and Science Or, Course Of Instruction In Strategy, Fortification, Tactics Of Battles, &C.; Embracing The Duties Of Staff, Infantry, Cavalry, Artillery, And Engineers; Adapted → online text (page 27 of 35)
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Saxe enabled the French to repel, with immense destruction, the attacks
of greatly superior numbers; to the battle of Fleurus, in 1690, where
the Prince of Waldeck exposed himself to a most disastrous defeat "by
neglecting the resources of fortification and other indispensable
precautions;" to the battle of Malplaquet, in 1709, where Marshal
Villars, by neglecting to occupy and intrench the farm that closed the
passage between the woods of Sars and Lanière, exposed himself to a
disastrous defeat; to the operations of 1792, where General Custine, by
neglecting to intrench the heights that covered Bingen, as the engineers
had recommended, exposed himself to those terrible disasters which
forced him to a precipitate retreat; to the works of Wervike, which, by
a vigorous resistance on the 10th of September, 1793, saved the Dutch
army from total destruction; to the intrenched camp of Ulm, in 1800,
which for six weeks held in check the victorious army of Moreau; to the
intrenched lines of Torres Vedras, in 1810, which saved from destruction
the English army of Wellington; to the field-defences of Hougomont,
which contributed so much to the victory of Waterloo, &c.

_Military communications._ - The movements of armies are always much
embarrassed by forests, marshes, and water-courses, and nothing
contributes more to the dispatch of military operations than the means
of opening practical and easy communication through these various
obstacles.

It is not necessary here to enter into any detailed discussion of the
manner of constructing military communications through forests or
marshes. In a new country like ours, where almost every one has had some
experience in road-making, no very great technical knowledge is required
for the construction of temporary works of this character; but much
professional skill and experience will be requisite for the engineers
who make the preliminary reconnaissances, and fix the location of these
roads.

Water-courses may be crossed by means of fords, on the ice, or by
ferries and bridges. When temporary bridges or ferries are constructed
by the army in the field, they are classed under the general head of
_military bridges_, or more properly, _pontoniering_.

Where the depth of the stream is not great, the current slight, and the
bottom smooth and hard, the passage may be effected by _fording_. If the
bottom be of mud, or large stones, the passage will be difficult and
dangerous, even where the depth and current are favorable. Under
favorable circumstances infantry can ford a stream where the depth is
not greater than four feet; cavalry to a depth of four or five feet; but
artillery, and engineer trains, cannot go to a depth of more than two
and a half feet, without greatly exposing their ammunition and military
stores The fords should be accurately staked out before the passage is
attempted, and ropes ought to be stretched across the stream, or cavalry
and small boats stationed below, to prevent the loss of life.

Ice may be crossed by infantry, in small detachments. Its strength may
be increased by covering it with boards, or straw, so as to distribute
the weight over a greater surface. By sprinkling water over the straw,
and allowing it to freeze, the mass may be made still more compact. But
large bodies of cavalry, and heavy artillery, cannot venture on the ice
unless it be of great thickness and strength. An army can never trust,
for any length of time, to either fords or ice; if it did a freshet or a
thaw would place it in a most critical state. Military bridges will,
therefore, become its only safe reliance for keeping open its
communications.

Military bridges are made with trestles, rafts, boats, and other
floating bodies. Rope bridges are also sometimes resorted to by troops
for passing rivers.

_Trestle bridges_ are principally used for crossing small streams not
more than seven or eight feet in depth: they also serve to connect
floating bridges with the shore, in shallow water. The form of the
trestle is much the same as that of an ordinary _carpenter's horse,_
i.e., a horizontal beam supported by four inclined legs. These trestles
are placed in the stream, from twelve to twenty feet apart, and
connected by string-pieces, (or _balks_ as they are termed in technical
language,) which are covered over with plank. The action of the current
against the bridge may be counteracted by anchors and cables, or by
means of boxes or baskets attached to the legs of the trestles, and
filled with stones. A more substantial form may be given to the bridge
by substituting for the trestles, piles, or the ordinary framed supports
so much used in the newer parts of our country.

For examples of the use of bridges of this description we would refer to
Caesar's celebrated bridge across the Rhine; the passage of the Scheldt
in 1588 by the Spaniards; the passage of the Lech in 1631 by Gustavus
Adolphus; the passage of the Danube in 1740 by Marshal Saxe; the great
bridge across the Var during Napoleon's Italian campaigns; the passage
of the Lech in 1800 by Lecourbe; the bridges across the Piava, the
Isonso, &c., in the subsequent operations of the army in Italy; the
celebrated passage of the Danube at the island of Lobau in 1809; the
passage of the Agueda in 1811 by the English; the passages of the Dwina,
the Moscowa, the Dneiper, the Beresina, &c., in the campaign of 1812;
the repairing of the bridge near Dresden, and the passage of the Elbe in
1813, &c.

_Rafts_ formed of timbers, casks, barrels, &c., are frequently used as
military bridges. They may be made to bear almost any weight, and will
answer for the passage of rivers of any depth and width, provided the
current be not rapid.

Where the bridge is to be supported by rafts made of solid timbers,
these timbers should be first placed in the water, to ascertain their
natural position of stability, and then the larger ends cut away on the
under side, so as to present the least possible resistance to the action
of the current. They are afterwards lashed together by strong rope or
withe lashing, or fastened by cross-pieces let into the timbers, and
held firm by bolts, or wooden pins. These rafts are kept in place by
anchors and cables placed up and down stream. The roadway is formed in
nearly the same manner as for a bridge supported on trestles. Empty
casks, and other floating bodies, may be substituted in place of logs in
the construction of rafts.

For examples of the use of rafts in the construction of military
bridges, we would refer to the passage of the Seine in 1465 by Count
Charolais; the passage of the Meuse in 1579, by Alexander Farnése; the
passage of the Vistula in 1704, the Borysthenese in 1709, and the Sound
in 1718, by Charles XII.; the passage of the Adige in 1796; the passage
of the Po in 1807; and the subsequent military operations in the Spanish
Peninsula.

Military bridges are frequently made of _boats_, and the ordinary
river-craft found in the vicinity of the intended passage. Flat-bottomed
boats are the most suitable for this purpose, but if these cannot be
obtained, keel boats will serve as a substitute. When these water-craft
are of very unequal sizes, (as is frequently the case,) two smaller
ones may be lashed together to form a single support; they can be
brought to the same level by means of stone ballast. The gunwales must
be suitably arranged for supporting the balks, or else frameworks should
be erected for this purpose from the centre of the boat. The arrangement
of the roadway, anchors, &c., is the same as before.

A _bridge-equipage_ made to follow an army in its movements in the
field, is generally composed of light skiffs or batteaux, and the
necessary timbers, planks, anchors, &c., for forming the roadway, and
keeping the bridge in its position. All these articles are constructed
especially for this purpose. All the wood-work should be of tough and
well-seasoned timber, so as to impose no unnecessary weight on the wagon
trains. The bateaux should also be made of strong and light materials.
For convenience in transportation, these boats are sometimes made with
hinges so as to fold up. The ribs are usually of oak, and the sides and
bottom of pine. Instead of plank, a covering of tin, copper,
India-rubber, &c., has sometimes been substituted. Floating supports of
this character are often made in compartments, so as to prevent their
sinking when injured by the enemy's projectiles. Indian-rubber pontons
may be folded up into a small space, and their slight weight renders
them convenient for transportation.

On navigable streams a part of the bridge resting on one or two bateaux
should be so arranged that it can be shipped out of its place, forming a
_draw_ for the passage of river-craft. Indeed, it would be well, even
where the river is not navigable, to form a draw for the passage of
trees, and other floating bodies, sent down by the enemy against the
bridge.

An ordinary bridge-equipage of bateaux, or light pontons, for crossing a
river of from three to four hundred yards in width, and of moderate
current, will require a train of from sixty to eighty wagons.[46] Under
favorable circumstances, and with a well-instructed corps of pontoniers,
the bridge may be thrown across the river, and prepared for the passage
of an army in a few hours at most.[47] After the troops have passed
over, the bridge may be taken up, and replaced on the wagons in from a
quarter to half an hour.

[Footnote 46: The number of wagons in a ponton train will be greatly
diminished if it be found that Indian-rubber boats may be used as
supports for the bridge. The engineer department of our army are making
experiments to determine this point.]

[Footnote 47: In 1746, three bridges of bateaux were thrown across the
Po, near Placentia, each fifteen hundred feet in length, and entirely
completed in eight hours. In 1757, two bridges of bateaux were thrown
across the Rhine, at Wesel, in half an hour; again, in the same year, a
third bridge was thrown across this river near Dusseldorf, in six hours.
In 1841, Col. Birago, of the Austrian army, arrived on the bank of the
Weisgerben arm of the Danube, with his bridge-equipage, at a round trot,
and immediately began the construction of his bridge, without any
previous preparation or examination. In less than three-quarters of an
hour the bridge was completed, and three loaded four-horse wagons passed
over on a trot, followed by a column of infantry.]

The following examples will serve to illustrate the use of different
kinds of boat-bridges in military operations: - the passage of the Rhine,
in 1702, by Villars; the passage of the Dnieper and the Bog, in 1739, by
the Russians; the passage of the Danube, in 1740, by Marshal Saxe; the
passage of the Rhine, near Cologne, in 1758, by the Prince of Clermont;
the passage of the Rhine, in 1795, by Jourdan; the passage of the Rhine,
at Kehl, in 1796, by Moreau; and again the same year, at Weissenthurn,
and at Neuwied, by Jourdan; the bridges across the Rhine, at the sieges
of Kehl and Huninguen, in 1797; the passage of the Limmat, in 1799, by
Massena; the passages of the Mincio, the Adige, the Brenta, the Piava,
&c., in 1800; the passages of these rivers again in 1805; the passages
of the Narew, in 1807, by the Russians; the several passages of the
Danube, in 1809, by the French and Austrian armies; the passages of the
Tagus and Douro, in 1810, by the English; the passages of the Niemen,
the Dwina, the Moskwa, and the Beresina, in 1812, by the French; and of
the great rivers of Germany and France, in 1813 and 1814.

A floating body, propelled from one bank to the other by the current of
the stream, is termed a _flying-bridge._ The usual mode of establishing
a ferry of this kind, is to attach the head of the boat by means of a
cable and anchor to some point near the middle of the stream. By
steering obliquely to the current, the boat may be made to cross and
recross at the same point. A single passage may be made in the same way,
by the action of the current without the cable and anchor, but the boat
in this case will be carried some distance down the stream. Rowboats are
employed for crossing over infantry by successive debarkations; but this
process is too slow for the passage of a large force; it may very well
be resorted to as auxiliary to other means.

Steam craft are so common at the present day on all navigable streams,
that an army in the field will frequently be able to avail itself of
this means of passing the larger rivers. But, in a hostile country, or
in one already passed over by the enemy, it will not be safe to rely
with confidence upon obtaining craft of this character. A well-organized
army will always carry in its train the means of effecting a certain and
speedy passage of all water-courses that may intercept its line of
march.

Flying-bridges or rowboats were employed in the passage of the Dwina, in
1701, by the Swedes; the passage of the Po, in 1701, by Prince Eugene;
the passage of the Rhine, at Huninguen, in 1704; Jourdan's passage of
the Rhine in 1795; Moreau's passage in 1796; the sieges of Kehl and
Huninguen in 1797; Massena's passage of the Limmat, and Soult's passage
of the Linth, in 1799; the passage of the Rhine, at Lucisteig in 1800;
the passage of the Po, by the French, just before the battle of Marengo;
and others in Italy, Germany, and Spain, in the subsequent campaigns of
Napoleon.

Military bridges have sometimes been formed of ropes, cables stretched
across the stream, and firmly attached at each end to trees, or posts
let into the earth. If the shore is of rock, rings with staples let into
the stone form the best means for securing the ends of the main ropes.
Plank are laid on these cables to form the roadway. The ropes forming
the "side-rail" of the bridge are passed over trestles at each shore,
and then fastened as before. Short vertical ropes attach the main
supports to these side ropes, in order that they may sustain a part of
the weight passing over the bridge. Constructions of this character are
fully described in Douglas's Essay on Military Bridges. For example, see
the passage of the Po, near Casal, in 1515, by the Swiss; the bridge
thrown over the Clain by Admiral Coligni, at the siege of Poitiers, in
1569; the operations of the Prince of Orange against Ghent and Bruges,
in 1631; the passage of the Tagus, at Alcantara, in 1810, by the
English; the bridge constructed across the Zezere, by the French, in
1810; the bridge thrown across the Scarpe, near Douai, in 1820; the
experiments made at Fêre in 1823, &c.

The passage of a river in the presence of an enemy, whether acting
offensively or in retreat, is an operation of great delicacy and danger.
In either case the army is called upon to show the coolest and most
determined courage, for its success will depend on its maintaining the
strictest discipline and good order.

In the case of a retreat the bridge should be covered by field
intrenchments, called a _tête de pont_, and defended by a strong guard.
If the river be of moderate width, the enemy may be kept at a distance
by heavy batteries on the opposite shore. As soon as the passage is
effected by the main body, the bridge, if permanent, will be blown up,
or otherwise destroyed by the miners, and if floating, will be swung
round to the other shore. The rear-guard will pass over in rowboats, or
the end pontons detached for that purpose. An army retreating in the
face of an enemy should never rely upon one single bridge, no matter
what may be its character: for the slightest accident happening to it
might expose the whole army to inevitable destruction.

The passage of a river by main force, against an enterprising and active
enemy on the opposite shore, is always an operation of the greatest
difficulty, and not unfrequently accompanied with the most bloody
results.

The most effectual method of accomplishing this object is by stratagem.
Demonstrations are made at several points at the same time: bodies of
troops are thrown across, after nightfall, in rowboats or by
flying-bridges, to get possession of the opposite bank. The vanguard of
light cavalry may cross by swimming. The pontoniers should have their
bridge equipage in readiness near the intended point of passage, so that
it can be thrown across with the greatest possible rapidity, while the
advanced guards are still able to keep the enemy at a distance. Under
favorable circumstances the pontoniers will have the bridge in readiness
for the passage of the army before the enemy can collect his troops upon
the threatened point.

Cannon-balls and hollow shot are the most effectual means for destroying
an enemy's bridge when our batteries can be planted within reach. When
this cannot be done, we must resort to fire-boats, floating rafts, &c.,
to accomplish our object. Operations of this kind carried on in the
night, are most likely to succeed.

To protect bridges from the action of these floating bodies, stockades,
or floating chevaux-de-frise are constructed across the stream at some
distance above the bridge; strong cables, or chains stretched directly
across the river, or with an angle up stream, may be used in place of
stockades, or in conjunction with them. Guards should be stationed above
the bridge, with boats, ropes, grapnels, &c., for the purpose of
arresting all floating bodies and drawing thorn ashore, or directing
them safely through the _draw_ in the bridge arrangement.

The troops especially charged with the construction and management of
the various kinds of military bridges, are denominated _pontoniers_. The
duties of these troops are arduous and important, and, in a country like
ours, intersected by numerous water-courses, the success of a campaign
will often depend upon their skill and efficiency.

_Sapping_. - This is a general term applied to the operations of forming
trenches, along which troops may approach a work without being exposed
to the fire of the besieged.

In addition to the ordinary sapping-tools, such as shovels, picks,
gabion-forks, &c., used in constructing trenches, there will also be
required a considerable amount of sapping materials, such as gabions,
fascines, sap-fagots, sandbags, &c.

The _gabion_ is a cylindrical basket of twigs, about two feet in
diameter, and some three feet in length, and without a bottom. It is
made by driving into the ground, in a circular form, a number of small
pickets about an inch in diameter, and of the length required for the
gabion. Twigs are wattled between the pickets like ordinary basket-work,
and fastened at the ends by withs or packthread. Gabions are used in
forming saps, batteries, blindages, powder-magazines, and in revetting
the steep slopes of field-works.

The _fascine_ is a bundle of twigs closely bound up, from nine to twelve
inches in diameter, and from ten to fifteen or twenty feet in length.
The largest are sometimes called _saucissons_. In making a fascine,
straight twigs about the thickness of a man's finger are laid side by
side, and firmly compressed together by a strong rope or chain attached
to the extremities of two levers. While held in this position the twigs
are firmly bound together by withs or cords. Fascines are used in
constructing trenches, batteries, &c., and for filling up wet ditches.

The _sap-fagot_ is a strong fascine about ten inches in diameter and two
feet in length, with a picket inserted through the middle. It is used in
the double sap in connection with gabions.

_Sand-bags_ are usually made of coarse canvass. When filled with earth
they are some six or eight inches in diameter, and from eighteen inches
to two feet in length. From their perishable nature, they are used only
when other materials cannot be procured, and where it is important to
place the troops speedily under cover from the enemy's fire.

Bales of wool, cotton, hay, straw, &c., may be employed in sapping for
the same purposes as the above materials, when they can be procured in
sufficient quantity. Pork and flour barrels, which are usually in
abundance in a camp, are frequently filled with sand and used for
forming magazines, blindages, &c., in field-works.

A trench constructed in ordinary soil beyond the range of the enemy's
grape, is called a _simple sap_, or ordinary trench. The earth is thrown
up on the side towards the place besieged, so as to form a kind of
parapet to cover the men in the trench. The labor is here executed under
the supervision of engineer soldiers, by working parties detached from
the other arms. Fig. 50 represents a vertical section of a simple sap.

When within range of the enemy's grape, the _flying sap_ is resorted to
in order to place the workmen speedily under cover. In this operation,
gabions are placed in juxtaposition on the side towards the besieged
work, and filled with all possible speed by the workmen. Three rows of
fascines are usually placed on the top of the gabions to increase the
height. The most difficult part of the flying sap is executed by
engineer troops, and the trench is completed by the ordinary working
parties. Fig. 51 represents a section of this sap.

The _full-sap_ is employed when the works of the besiegers are within
range of musketry, or when the grape fire of the besieged is so deadly
that the flying sap can no longer be used. This is a difficult
operation, and unless executed with great care and by well-instructed
engineer troops, the construction of the trench will be attended with an
immense loss of life. The work must be executed under cover of a
_sap-roller,_ which is a cylindrical mass of fascines, wool, or cotton,
some two feet in diameter. On very smooth ground a ball-proof shelter on
wheels might be used as a substitute. The sap-roller being placed along
the line of the trench so as to cover the sapper in front, who is armed
with a musket-proof headpiece and cuirass, this sapper commences the sap
by placing a gabion on the line of the proposed trench and fills it with
earth, working on his hands and knees. Having filled the first gabion,
he pushes forward the sap-roller and places a second one next the first,
stopping the open joint between the two with a stop-fagot. The second
gabion being filled in the same manner as the first, others are
successively established. When the first sapper has advanced a few feet,
he is followed by a second, also in defensive armor, who increases the
excavation and embankment; this sapper is then followed in the same way
by a third and a fourth, after which the trench will be sufficiently
advanced to be turned over to the ordinary workmen. The sap-fagots may
be removed when the embankment becomes thick enough to resist grape.
Fig. 52 represents a plan and section of a full-sap.

When the direction of the trench is such that the men are exposed on
both sides, it will be necessary to throw up an embankment both to the
right and left. This operation is called the _double sap,_ and is
executed by two parties of sappers, working side by side. In this sap it
will be necessary to frequently change the direction of the trench, or
to throw up traverses, in order to cover the men at a distance from the
sap-roller. Wing-traverses, on the side of the trench which is least
exposed, some times serve the same purpose as a double sap.

_Mines_. - By _mining_, as a military term, we understand the operations
resorted to for the demolition, with powder, of a military structure of
any description. The term _mine_ is applied both to the excavation
charged with powder for the purpose of producing an explosion, and to
the communications which lead to this excavation.

The place in which the charge of powder is lodged is called the
_chamber_, the communication by which this place is reached the
_gallery_, and the excavation made by the explosion is termed the
_crater_.

The form of the crater caused by an explosion in ordinary soils is
assumed to be a truncated cone, the diameter, _c d_, (Fig. 53,) of the
lower circle being one-half the diameter, _a b_, of the upper circle.
This form has never been ascertained to be exactly correct, but the
theoretical results deduced from a mathematical discussion of this
figure have been fully verified in practice. The radius, _p b_, of the
upper circle is termed the _crater radius_; the line _o p_, drawn from
the centre of the charge perpendicular to the surface where the
explosion takes place, is termed the _line of least resistance_; the
line _o b_, drawn from the centre of the powder to any point in the
circumference of the upper circle, is termed the _radius of explosion_.

When the crater radius is equal to the line of least resistance, the



Online LibraryHenry Wager HalleckElements of Military Art and Science Or, Course Of Instruction In Strategy, Fortification, Tactics Of Battles, &C.; Embracing The Duties Of Staff, Infantry, Cavalry, Artillery, And Engineers; Adapted → online text (page 27 of 35)