468 
ATTACK OF A MODERN LAND FORTRESS. 
Entrenched 
Camps and 
their objects. 
by the Howitzer Batteries of the attack once its position has been dis¬ 
closed by its opening fire. 
Class (4.) Light Howitzers .—The light howitzers are expected to 
be useful in the defence by employing shrapnel, but the value of such 
fire is very doubtful. It must always be inaccurate, the bullets have a 
very low velocity and a small danger zone, and it would be extremely 
difficult, if not impossible, to regulate shrapnel fire from behind cover 
against troops in motion ; it may be used with some effect against the 
light guns of the attack, and some further remarks will occur under 
that heading. It would also be an effective bar against approach by 
sapping. 
Balloons .—These have frequently been spoken of as a very certain 
means of discovering concealed batteries and observing the effects of 
fire at them, but experiment has shown that they are not safe from 
shrapnel fire of field guns at a less range than 3600 yards, and at that 
distance and at a height of 1500 feet (which would, perhaps, be the 
limit for a captive balloon) the angle which an observer’s line of sight 
would make with the horizontal would be 9°; that is to say, a battery 
within 70 yards of a hill giving 30 feet of cover would be invisible. 
Now this is an extremely small amount of cover, and the battery could 
be placed nearer than 70 yards with more certainty of concealment 
when using smokeless powder. In any case the experience of those 
who have tried observation of fire from balloons, is that it is of doubt¬ 
ful value even in very calm weather and quite impossible in a wind 
owing to the rapid motion. It is also quite a matter of opinion whether 
a balloon would be safe from Artillery Fire even at 4000 yards range; 
there is no reason why it should be considered so. 
Even if the existence of a battery behind a hill is suspected, it can 
only be attacked by the very uncertain method of C( pendulum fire ” 
(successive rounds fired at different elevations on the chance of hitting). 
Balloon observation requires a clear view of the objective and excep¬ 
tional conditions of weather, and its value under service conditions is 
probably entirely theoretical. 
In concluding this portion of our subject it is well to remember what 
the chief objects of these large fortified places are. The French frontier 
defences, for example, are intended in the first place to delay an invader 
by obliging him to besiege one or more of the entrenched camps before 
advancing, thus giving time for the Field Armies to mobilize under 
cover of the fortress; and, secondly, as points on which an army, beaten 
in front, might retire, and from which, after being re-organized, it 
might again undertake offensive operations; but the regulations par¬ 
ticularly enjoin that a Field Army is not to allow itself to be shut up 
in one of these entrenched camps, and one of the principal uses of 
their garrisons is to be able to undertake active offensive operations 
against the flanks of an invading army which may attempt to pass 
them. Passive resistance forms no part in the principles governing 
the design of the modern fortress. 
Some stress is laid on this point because, when we come to consider the 
question of choice of positions for the Siege Batteries of the attack, and 
insist on the necessity for concealment, it may be objected that there 
