taking steps to reinforce his lines. Thus an attacking army can always ensure a local numerical superiority at the decisive moment, and the issue will largely depend on whether this advantage is sufficient to outweigh the tactical advantage of the defending force as due to its choice of position and entrenchments and other defensive works. Clearly much, if not everything, depends upon the general in command of the attack being able successfully to conceal his movements until the moment arrives for delivering his blow. But the veil of secrecy has been lifted by the advent of aircraft. It is for this reason that the power of aerial reconnaissance has proved so valuable a weapon to the defending force, and of comparatively little value to the attack. It is quite true that the aircraft of the attacking force may be of considerable use in reporting the nature and strength of the defences, and so may disclose the points of weakness at which the chances of successful assault are the greatest: but this will only in a very small degree compensate for the premature disclosure of the whole plan of attack to the defenders, a disclosure which, if we may judge from experience so far gained, appears to be little short of complete.
The foregoing applies more particularly to warfare in which large bodies of troops are engaged over a great extent of territory; evidently where fighting is on a small scale, and the whole of the movement constituting a concentration and attack can be executed between sunset and sunrise, the operations can be considered to be of a purely tactical character. It may be emphasised that it is by destroying the strategic advantage hitherto enjoyed by the attack that aeronautical reconnaissance gains its especial value as an aid to the defence. Thus, so far, the advent of aircraft in the field of battle has had the effect of tending to produce a deadlock, or position of stalemate, such as we are able to witness at the present
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