le, I managed to get clear of
Antwerp, reaching Bruges again at 3.15 a.m. At 4 a.m. we set out and
found a very wet machine in a wetter field and after considerable
difficulty and flying through the top of the surrounding hedge,
struggled into the upper air on the way back to Headquarters at
Fere-en-Tardennois.

During the Battles of the Aisne and of Ypres strategical reconnaissance
was carried out by the few machines available at Headquarters. Shephard,
the best reconnaissance officer I have ever known, who was killed later,
used to fly his B.E.2 without observer over the greater part of Belgium
two or three times a week and always brought in a long, closely packed,
and extraordinarily valuable report. Tactical reconnaissance to a depth
of 15 to 20 miles was done by units attached to Corps.

After the Battle of the Aisne, which was the turning point in the
evolution from the war of movement to trench warfare, pure
reconnaissance, though still the basis of air work, tended to become a
matter of routine, while many new and specialized forms of it--such as
air photography and artillery spotting by wireless--were developed.

_Photography._

Though experiments had been made in the problem of photography from the
air before the war, principally by Fletcher, Hubbard and Laws, and its
value to survey was recognized, it had not become of practical utility.
We only took one official camera with us to France on August 13th, 1914,
and it was not until September 15th that the first attempt at air
photography was made, when five plates were exposed over positions
behind the enemy's lines with very imperfect results. Its great value as
an aid to observation in trench warfare was, however, very apparent,
fresh brains were brought to the task, Moore-Brabazon, Campbell and Dr.
Swan, and by the end of the year better success was obtained, though
positions even then had to be filled in by the observer with red ink.
Experiments at home during 1915 led to a great improvement in lenses,
and at the beginning of 1916 air photography was universal. At the
Battle of the Somme new enemy positions were photographed as soon as
they were seen, and the camera did invaluable work in the reconnaissance
of the Hindenburg Line during the German retreat of 1917, and the taking
of over a thousand photographs was a daily occurrence. On September 4th,
1917, a record of 1,805 photographs was made.

The development of air photography, very remarkable in