Surprises, when thought possible, are undertaken under the cover of night, fog, or severe storms. The tactical disposition of the troops is similar to that used in open assault, the columns being preceded by ladder-parties for scaling walls, engineers for blowing down barriers, etc., etc., according to the nature of the case, and followed by a large reserve which is designed to hold any points captured by the advancing columns. It is usually considered best to make simultaneous attacks at several points, in order to confuse and divide the defence, holding the main reserve nearest to the column which is expected to succeed; but making provision also for promptly and fully supporting any other party which may have forced an entrance into the work. An entrance secured, consecutive points should be occupied and held, preserving communication between them, and avoiding too great dispersion of the troops, until a foothold is gained which can in all probability be held against the defence. After this greater boldness may be used in attacking important points within the place.
The complete capture of the work and its garrison cannot ordinarily be expected, however, until daylight allows the systematic movement of the attack throughout the place. In case of failure, any captured gate must be held if possible until all the troops have retreated through it and are covered by the reserves.
DEFENCE AGAINST SURPRISE.
3. The measures necessary to guard a fortified place against surprise are of two classes. First, for its prevention, by use of all the usual outposts and interior guards,—the organization and duties of which need not be repeated here,—and of telegraphic and other signals and communications with the surrounding country by which the approach and movements of any attacking force may be made known before it comes near the work.
Second, for its repulse, by so training and disciplining the garrison that, upon the alarm being given, the parapets, batteries, etc., will be manned and all defensive measures will be taken before the assaulting body can enter the work.
This will be accomplished by so thoroughly drilling the garrison in its duties that each man will go at once to his proper station fully equipped for his duties at any hour day or night, without confusion or unnecessary excitement. The subsequent measures are the same as for resisting any other assault.
ASSAULT.
4. By an assault is meant an open attack upon a position by troops in line or column.
Formerly it was recommended to make assaults at early dawn, in order to have the increasing daylight for securing the results of victory; more recently night attacks have been more strongly advocated in order to diminish the losses from the fire of the defence while making the attack, and the still greater ones which follow a repulse when, the fire of the supports and reserves of the attack being suspended for fear of injuring the retreating troops, the defence pours upon the latter the full close and deadly fire of all its arms. Whether the advantages of a night attack more than counterbalance the dangers resulting from the confusion due to darkness is, however, a question not yet settled.
Open assaults upon fortified positions, well manned and armed, have, since the introduction of firearms, been considered the most bloody, uncertain, and frequently the most unjustifiable operations in war. With the introduction of machine and rapid-fire guns and magazine rifles it may be considered as an established fact that a well-defended line cannot be carried by an assault in front until its fire is overpowered or its ammunition exhausted.