LAND AND WATER 
April 24, 1915. 
the Eastern si..pe; and if the invading array 
carried the crest it would be impossible to defend 
the short, steep escarpment down on to the Severn 
yalley. 
But with a great mountain range the dis- 
tances involved are so considerable that this 
analojgy does not apply. 
With the crest already in one's hands, one 
still has a belt of territory at least a day's march 
broad, and usually nmch more, to pass before one 
is out of the wild country and free to use the 
numerous aud easy communications. 
Consequently, the real strain upon an army 
which is trying to force a belt of mountain terri- 
tory comes at the end of its effort, so far as com- 
munications are concerned, and just as it is reach- 
ing the further plain it is putting the maximum 
strain upon its columns of supply. 
. T L A I N Easij cominunica^LOi 
especLOJ^ La£i£ralkf. 
^ thus 
ut 
Next we must note that when once the Plains 
are reached the army reaching them has a very 
great advantage at once over his opponent. This 
advantage is not only due to the fact that once the 
obstacle has been surmounted, and once the 
" bridge heads," so to speak, have been established 
on the further side of it — that state of affairs 
applies to the successful crossing of any obstacle — 
the particular advantage given by the forcing of a 
mountain chain and arrival upon the plain beyond 
may be compared to bursting of water through a 
dam. So much effort and such numbers are required 
for the difficult passage (which, remember, can only 
necessarily be conducted by a large body upon a 
certain breadth of front), that if "^it is successful, 
by the time its effort reaches the plains the 
enemy is probably already beaten. This does 
not apply to the case of a deliberate retire- 
ment behind a mountain range on the part 
of the defence, when the defence feels itself 
nnequal to the task of holding the hills; but 
it does apply to such a battle as this which is 
raging in the Carpathians on the Hungarian side. 
An army which shall have been forced down the 
Hungarian slope on to the plains will hardly be in 
a posture to defend those plains against the masses 
that have been accumulated against it, and that 
have forced it from the hills. 
This consideration, though it is very vague 
and general in its character, explains, I think, 
more than one of the successful irruptions over a 
mountain chain in history. At first blush it would 
seem as though the army in the plain had every 
advantage. It has good communications behind 
it, whereas the army coming across the mountain 
has bad communications. It has probably also 
shorter communications behind it. It can move 
large bodies with rapidity laterally, whereas the 
army that has only just arrived on the plains can 
only move small bodies laterally, and probably not 
with rapidity. It has destroyed or impeded the 
communications which it left behind, whereas it 
has kept intact the communications upon which it 
reposes. 
From all these causes it would seem that the 
army which has been pressed back across the 
mountains should be in a better posture than the 
army wJiich has forced the obstacle. But the his- 
torical cases which in practice prove the contrary 
are so numerous that they call for an explanation, 
and I believe the explanation to be what I liave 
said — that the effort to force such an obstacle 
being what it is, when it is successful has all the 
effect of the bursting of w^ater through a dam, 
and, the plains being reached, the momentum of 
victory counts for more than all the rest. 
I repeat, however, that this does not apply 
to the case of the defensive voluntarily abandon- 
ing a belt of mountain district before a superior 
offensive which it thinks it is not able to meet. In 
this latter case the defensive, having fallen back 
on to the plains, is in a very good posture to meet 
the offensive proceeding from over the mountains. 
It compels that oft'ensive to fight with an obstacle 
at its back, and that is always a handicap, and it 
has the advantages above enumerated which the 
plain can give. 
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