August 14, 1915. 
LAND AND "E A T E E , 
SUBSIDIARY OPERATIONS. 
By John Buchan. 
TWO terms which are common in military; 
literature have lately taken to appear- 
ing in conversation — " isubsidiary " and 
" divergent " operations. These are 
what lawyers cafi " terms of art," and do not bear 
whatever significance the user chooses to give 
them. A suteidiary operation is something which 
directly subserves the main purpose of a cam- 
paign; a divergent operation is one which has 
no connection with the main campaign, except 
that it is directed against the same enemy. A 
subsidiary operation is, so to speak, a flying 
buttress to a building : a divergent operation is a 
rival structure half a mile off. Hence we usually 
use " subsidiary " with a tone of approval, and 
-" divergent " with an accent of blame. 
This is right, provided that the divergent 
operation is planned and carried out by the 
authorities diluting the main campaign. In TESTS OF A SUSIDIARY OPERATION. 
from the north-east, then within the last montS 
from the south-east, and now, again, as we write, 
from the north-east. But each time they used in 
the effort all the striking force they could spare. 
On the other hand, last October in ^West Flanders 
they showed a curious division of mind. In the 
struggle for the Channel ports they attacked 
simultaneously at Arras, at La Bassee, on tJie 
Yser, and at Ypres, when, if they had succeeded 
at either of the first two places, everything else 
would have fallen into their hands. The result 
was that they succeeded nowhere. That is " diver- 
gency " of the most heinous kind. But to pre- 
vent confusion it is better to keep the term, not 
for side-shows within the main campaign, but for 
separate and subsidiary operations in dif- 
ferent terrains. 
that case it implies a dissipation of strength and 
an infirmity of purpose. But it should be noted 
that in certain cases a divergent operation is in- 
evitable and justifiable. A colony may find it 
necessary for its own interests, while the Mother 
Country is at war, to strike at a local settlement 
of the enemy. It is perfectly true that the great 
issue will be decided in very different fields, and 
that in the event of the enemy being beaten all his 
overseas possessions will be at the mercy of the 
victor. But local feeling must be taken into 
account, and it is natural that a locality should 
wish to strike at the nearest hostile territory. It 
is desirable, too, inasmuch as it gives that locality 
a chance of immediate participation in the great 
struggle, and so strengthens the common purpose 
of the Empire. Instances may be found in the 
present war. The conquest of Germany's Pacific 
Islands by Australia and New Zealand was a 
divergent operation, inasmuch as it did not affect 
the main issue in Europe, and the fate of these 
territories would in any case have been deter- 
mined by the result of the European struggle. 
The same is true of General Botha's brilliant 
conquest of German South- West Africa. But 
these local campaigns did much for Imperial 
prestige, and they were of incalculable value in 
uniting Australasia and South Africa in a 
common Imperial purpose. Again, an ally, who 
for some reason or other is unable to participate 
in the main theatre, may well direct its efforts 
against some outlying enemy possession. Such was 
Japan's capture of Tsing-tau. Had these opera- 
tions been undertaken by the General Staffs of 
the Allies in Europe and by forces which would 
otherwise have gone to the main theatre, they 
would have been properly condemned as divergent. 
As it was they remain divergent, but they are 
rightly approved. 
Again, the term " divergent " is not properly 
to be applied to a division of strength within one 
campaigning area. It is allowable to try first at 
one point on a battle front and then at another. 
Napoleon at Waterloo attacked at different 
poinLs. but successively, and in each case with all 
his might. The Germans in the East made a 
great frontal attack UDon Warsavf. then another 
There are three questions which we may ask 
ourselves about an operation in order to discover 
if it is truly subsidiary, and therefore legitimate. 
The first is : Is it profitable ? Will its success 
directly aid the chances of victory in the main 
theatre ? I assume that the operation in question 
is conducted by the central authorities of a belli- 
gerent Power, and that, therefore, if it is diver- 
gent it is blameworthy. 
Tried by this test, many of the operations in 
British history must rank as awful warnings. In 
the wars of the Revolution Pitt's passion for 
acquiring sugar islands led to expeditions which 
had no bearing on the main European conflict, 
and cost us many thousands of our best soldiers. 
In 1793, for example, we coasted about the globe 
like some traveller in search of rare orchids. In 
Europe we could not make up our mind which 
was the best place to strike, so we sent an expedi- 
tion under the Duke of York to the Netherlands ; 
we hung on to Toulon, and we dispatched an 
army to La Vendee. A year later we divided our 
energies between Guiana, South Africa, and a 
futile landing in Quiberon Bay, thereby playing 
wholeheartedly the game of the French Govern- 
ment. In 1807 we adventured at the Cape, Buenos 
Aires, Valparaiso, and Mexico. The point for 
criticism is not the failure of these escapades, but 
the fact that they were undertaken at all. 
Napoleon, undistracted by our overseas expkits,*- 
advanced by way of Jena and Friedland to a 
settlement with Russia. The younger Pitt vs^as 
a very great man, but he was a bad War 
Minister. He had not the flair of his father for 
detecting the weak points in the enemy's harness 
and striking hard. 
ITS FEASIBILITY. 
The second question is less easy to answer : 
Has the expedition a reasonable chance of suc- 
cess ? It is harder to decide upon this than upon 
the question of relevancy, and the danger is that 
a movement may be undertaken because ot its 
great and obvious fruitfulness when the odds are 
heavily against its succeeding. The Walcheren 
