Elements of Military Art and Science by Henry Wager Halleck (books you have to read txt) 📕

bank of the Rio Grande. Again if we compare our loss in other Mexican battles with that which the Americans sustained in their attacks upon Monterey, Churubusco, Molino del Key, and Chapultepec,—places partially secured by field works—we shall be still more convinced of the value of temporary fortifications for the defence of military positions, although it was manifest that the Mexicans neither knew how to construct nor how to defend them.

Nor was there much practice in this war in the use of military bridges, for, with the exception of the Rio Grande, our armies had no important rivers to cross. We must not, however, omit to note the important fact that General Taylor was unable to take advantage of the victories of Palo Alto and Resacade La Palma to pursue and destroy the army of Arista, because he had no pontoon equipage to enable him to follow them across the Rio Grande. It should also be remarked that even a very small bridge equipage would have been of very great use in crossing other streams and ravines during the operations of this war. One of our cavalry officers writes:—

"On our march from Matamaras to Victoria and Tampico, in 1846
and 1847, we had infinite difficulty in bridging boggy streams (there
being no suitable timber), and in crossing ravines with vertical banks;
a few ways of the Birago trestles would have saved us many days and
a vast amount of labor. In the operations in the valley of Mexico, our
movements, checked as they so often were by impassable wet ditches
and sometimes by dry ravines, would have been rendered so much more
free and rapid by the use of the Birago trestles, that our successes
could have been gained at far less cost, and probably with more rapidity
than they were."

With regard to military reconnaissance, the splendid achievements of Lee and others connected with the operations of General Scott, proved the value and importance of this particular branch of field engineering.

But field engineering, as a branch or arm of the military service, received its greatest development and most brilliant application in the Crimean war, particularly in the siege of Sebastopol, and the measures resorted to by General Todtleben to defend that place against the attack of superior forces.

A brief sketch of these defensive works may be of interest to the reader:—

When the allies reached Balaklava, Sebastopol was defended on the south side only by a loop-holed wall about four feet and a half thick, and from eighteen to twenty feet high, and a semicircular redoubt with two stories of loop-holes, and five guns in barbette. These works would have afforded some protection against a coup-de-main by infantry and cavalry, but could have offered no very considerable obstacle to a combined attack of these arms with artillery.

The Russian engineer commenced his operations for strengthening this position by occupying the most important points in his line of defence with detached field works of sufficient relief to resist an assault, and generally closed at the gorge. These works were afterwards connected by re-entering lines of a weaker profile, which served to enfilade the ravines and to flank the advanced works. The old wall was strengthened with earth, and rifle-pits for sharpshooters were constructed at a considerable distance in front.

The most important points of the main line of defence were: 1st. The Flag-staff Bastion. 2d. The Central Bastion. 3d. The Malakoff. 4th. The Redan. 5th. The little Redan. The command of the first was about fifteen feet, its ditch thirty feet wide and from twelve to fifteen feet deep. A portion of the scarp was provided with palisades some ten feet high. The construction of the Central Bastion was similar to that of the Flag-staff, but weaker in profile. The relief of the other works was still less. The command of the Malakoff was about fourteen feet, its ditch eighteen feet wide and twelve feet deep. The thickness of parapet in these works was generally about eighteen feet, and the bombproofs were covered with timber eighteen inches thick and six feet of earth. The loop-holed walls connecting these works were covered by a rampart and parapet, or entirely replaced by a simple parapet. Many of the embrasures were revetted with the common boiler iron ships' water-tanks filled with earth. The same material was sometimes used for traverses. Rope mantelets were used to protect the artillerists at the pieces from rifle balls and small grape. Great attention was given to the construction of bombproofs to cover the men from vertical firing. These were sometimes under the rampart and the second line of defence (where there was one), often under special traverses, or entirely under ground, and occasionally excavated in the solid rock. Some had fireplaces and chimneys, and were well ventilated. Interior slopes were revetted with gabions, crowned by fascines and sand bags. Gabions were also employed to repair the damage caused by the enemy's artillery. Abattis, military pits, caltrops and spikes, stuck through planks, and explosive machines were employed in front of different parts of the defences. Mines were resorted to in front of the Flag-staff Bastion to retard the French approaches. They were made in rocky soil with craters from twelve to fifteen feet deep. The Russian counter-approaches generally consisted of flêches, united by a simple trench.

Captain McClelland, one of our officers sent to the Crimea, from whose valuable Report most of the foregoing details are gathered, adds the following remarks upon these works of defence:—

"From the preceding hasty and imperfect account of the defences
of Sebastopol, it will appear how little foundation there was for
the generally-received accounts of the stupendous dimensions of the
works, and of new systems of fortifications brought into play. The
plain truth is, that these defences were simple temporary fortifications
of rather greater dimensions than usual, and that not a single new
principle of engineering was developed. It is true, that there were
several novel minor details, such as the rope mantelets, the use of
iron tanks, etc., but the whole merit consisted in the admirable
adaptation of well-known principles to the peculiar locality and
circumstances of the case. Neither can it be asserted that the plans
of the various works were perfect. On the contrary, there is no
impropriety in believing that if Todtleben were called upon to do
the same work over again, he would probably introduce better close
flanking arrangements."

"These remarks are not intended to, nor can they, detract from the
reputation of the Russian engineer. His labors and their results will
be handed down in history as the most triumphant and enduring monument
of the value of fortifications, and his name must ever be placed in the
first rank of military engineers. But, in our admiration of the
talent and energy of the engineer, it must not be forgotten that the
inert masses which he raised would have been useless without the skilful
artillery and heroic infantry who defended them. Much stronger places
than Sebastopol have often fallen under far less obstinate and
well-combined attacks than that to which it was subjected. There can be
no danger in expressing the conviction that the siege of Sebastopol
called forth the most magnificent defence of fortifications that has
ever yet occurred."

We will now pass to the works of attack. When the allies decided that the works of Sebastopol could not be carried by a simple cannonade and assault, but must be reduced by a regular siege, the first thing to be considered was to secure the forces covering the siege works from lateral sorties and the efforts of a relieving army. The field works planned for this purpose were not of any great strength, and many of them "were only undertaken when a narrow escape from some imminent danger had demonstrated their necessity." The French line of defence consisted of eight pentagonal redoubts, connected by an infantry parapet. The English seemed to attach but little importance to field works for the defence of their position; the terrible slaughter at Inkerman was the natural consequence of this neglect.

In describing the engineering operations of the allies at this siege. Captain McClelland says:—

"In regard to the detailed execution of the French attacks, little or
nothing novel is to be observed. Even when coolly examining the
direction of their trenches, after the close of the siege, it was very
rare that a faulty direction could be detected; they always afforded
excellent cover, and were well defiladed; in some cases the excavation
of the double direct sap was carried to the depth of six and a half feet
in the solid rock! The execution of many of the saps and batteries was
worthy of a school of practice. In the parallels, bombproofs were
provided as temporary hospitals, offices for the generals on duty, etc.
They did not use the sapper armor. The use of the sap-roller was
often attempted, but it could be employed only during the latter part of
the attack upon the Malakoff, when the fire of the Russian artillery was
nearly extinguished by the mortars; before that, as soon as a sap-roller
was placed in position—some thirty guns would be brought to bear
upon it, the result being its immediate destruction. It may justly be
said of the French approaches, that they admirably carried into practice
their system of sapping. The technical skill and patient courage
evinced by their officers and men in pushing forward such excellent
approaches, under a most deadly fire, is worthy of all commendation, and
is such as might have been expected from the antecedents of their
corps of engineers."

"With regard to the English, the case was different; it seemed as
if they systematically abandoned the excellent system taught and
perfected with so much care at Chatham. Whenever the ground was
difficult, their trenches generally ceased to afford shelter; a
shallow excavation in the rock, and a few stones thrown up in front,
appeared to be all that was considered necessary in such cases. They
were often faulty in direction as well as in profile, being not
unfrequently badly defiladed, or not gaining ground enough and
entirely too cramped; nor were they pushed as close to the Redan as
they ought to have been before giving the assault. In too many
cases the expression 'tâtonnement of the French would seem
to convey the best idea of their operations. Their batteries, however,
were very well constructed. The magazines, platforms, etc., were
usually similar to those adopted at Chatham, although
unnecessary deviations were sometimes complained of. They
employed neither armor nor the full sap, sometimes the half-full, but
generally the flying-sap were employed."

It may also be added, that, at the time of the assault, the French approaches had been pushed to the distance of thirty-two paces of the counterscarp of the Malakoff, while the English had scarcely reached within two hundred and twenty-five yards of the ditch of the Redan.

This description of the operations of the English at the siege of Sebastopol carries the professional reader directly back to their sieges in the Spanish Peninsula. It certainly is very strange that a great nation leading the van of civilization should, after such experience, have neglected to provide its army with a proper number of engineer officers and engineer troops, well instructed in the peculiar and difficult duties of that arm. What excuse can ever be offered for substituting human life for professional skill in the operations of a siege, when that skill may so readily be acquired in time of peace, and is always so necessary an element of a good military organization!

While every one admits that the siege of Sebastopol proved the immense importance of field-works against land attacks, some would conclude from the operations of that siege that good earthen works of a large development are better suited for the defence of a large city than permanent fortifications with masonry revetments, and which will necessarily have a less extended line of fire and less capacity for men and