he 14th a battle had been fought
east of Metz which had resulted in the French retreat. On the morning of
the 16th Moltke thought the French had retired west by the Metz-Verdun
road and those to the north of it, and consequently he directed his left
wing due west towards the Meuse to head off the French, sending his
right army towards Rezonville to harass their rearguard. The French
retreat, however, had been slow and two corps were still at Rezonville,
while three corps and the reserve cavalry were within easy reach, some
130,000 men in all. At 9 in the morning the German 3rd Corps, unaided
and far from support, attacked a position within reach of the whole
French Army, believing it had to deal with a rearguard only. Bazaine, on
the other hand, thinking that he was faced by the German main army,
remained on the defensive, and lost the opportunity of defeating in
detail first the 3rd and then the 10th German Corps. A few aeroplanes
operating on a radius of 30 miles would have disclosed between daybreak
and 10 a.m. the true position to either commander. Neither the German
nor the French cavalry, though both were engaged, obtained any reliable
information.

The problem as to how far aircraft would reduce the value of cavalry was
widely discussed before the war. It was seen that by day aircraft could
obtain quicker and more accurate information, but that cavalry retained
their power of night reconnaissance, of mobile offensive action and of
pinning the enemy to his ground by fighting. This was found to be so
during the retreat, when, in addition to the direct value of aircraft
for long-distance reconnaissance, an indirect asset of great importance
lay in the release of the cavalry for battle action in assistance of the
infantry. The question has become more acute since the offensive action
of aircraft against ground targets has developed, but although we must
never forget the splendid work of the mounted arm during the Retreat
from Mons, and in March, 1918, factors have arisen tending to make the
use of cavalry a problem of extreme difficulty in European wars, and it
is possible that, in addition to their reconnaissance functions,
aircraft will supersede the shock tactics and delaying action of
cavalry, though this may be modified if, the sabre being a thing of the
past, cavalry are converted into mounted machine gunners.

Air tactics and training were, therefore, chiefly studied from the point
of view of reconnaissance.