July 31, 1915. 
LAND AND .WATEE. 
THE POLISH TRIAiNGLE. 
But supposing that the Narew line grows 
and that the railway behind it is at the mercy of 
the German advance, there still remains that other 
thesis of which I spoke, the thesis which main- 
tains that a fortified area of such a sort as the 
Polish triangle is impregnable. 
In that case the mere existence of Brest, Neo 
Georgievsk, and Ivangorod would prevent an 
enemy's holding the bridges of .Warsaw and the 
Vistula line. 
Let U8 examine the validity of this thesis 
under modern conditions, and the consequent 
chance of the Russians maintaining their hold 
upon the Vistula line in spite of the loss of the 
JNarew. The theory of the triangle of fortresses 
can, perhaps, be grasped by consulting the follow- 
ing Sketch v., which is at once a simple example 
of the theory, and drawn upon the same scale as 
the actual three fortresses of Poland. 
In this sketch the circle marked A stands 
for the range of the batteries round the depots 
and barracks of Neo Georgievsk. The circle 
marked B stands for similar ranges surrounding 
Ivangorod. That marked C stands for similar 
ranges surrounding Brest. The point which it is 
important to prevent the enemy from permanently 
occupying is Warsaw, at D. From the rim of B 
to the rim of C is about 65 miles, much the same 
distance separates the rims of A and B, while 
from A to C is more like a hundred miles. 
The idea of a triangle of fortresses like this 
IS that the moment the enemy tries to get at D (or 
any other point within the sacred boundaries), 
whichever side he attacks from, or even if he 
attacks from all sides, he must necessarily be up 
against the following difficulty the moment any 
body of his penetrates beyond the line joining any 
two fortresses on either side of it, his communi- 
cations will be menaced by the forces within those 
fortresses, as well as by the defending field army. 
He cannot safely get into the triangle so long as the 
garrisons of the fortresses remain intact, for it is 
only a couple of days' march, or three days, at the 
most, from the most distant of the fortresses to a 
mathematical point immediately between them. 
Now, a large army marches, of course, on so broad 
a front that its flanlcs would be quite close to either 
fortress if it made the attempt to invade the 
triangle. 
The general of the White Army could not get 
in between A and C, for instance, on Sketch \^ 
without having the garrisons of both A and C 
striking him at his weakest point, that is his two 
flanks (at ^ and /) while he was tackling the field 
army of his enemy, which field army I have in- 
dicated on Sketch V. by the shaded oblongs 
opposite the invaders' white oblongs. The garri- 
sons from C and A would come up along the 
arrows and threaten both flanks and the communi- 
cations of the White, or invading army. He must, 
therefore, lay siege to and reduce (or at the very 
least " mask," that is, cut off by a screen of men) 
either fortress A or fortress C, or both. 
But whenever he sits down to lay a siege, or 
to mask a fortress, he detaches and immobilises 
very large numbers of men, and his enemy's army 
in the field attacks him in this unfavourable 
posture, aided by the garrisons of the two other 
fortresses, which thus support their beleaguered 
colleague. 
Supposing, for instance, in this Sketch VI., 
the White invading army proposes to isolate A, or 
capture it, so that an advance may later be made 
on D by such a line as (1) (1) without fear; then 
this invading White Army would have, say, half 
Its force occupied in trying to reduce A, and only 
the other half left to deal with the whole of it^ 
enemy's field army, represented by the shaded 
oblongs in Sketch VI., while the garrison of C 
would come up in flank along the arrow (2), and 
the garrison of B would come up in aid of the 
detending shaded army along arrow (3). The 
weakness of the White invader in such a case 
being due to the fact that you want a much larger 
number of men to take, or even invest, a fortress 
than you do to defend it. 
So, whichever way you look at it, and what- 
ever the invader does, he is, according to this 
thesis, at so grave a disadvantage once he gets 
within the boundaries of the triangle, that he will 
be exhausted or beaten before he has attained his 
object within those boundaries. 
Now it is clear that the value of this thesis 
depends upon certain characters that were true 
