pared positions along the Aisne, there
commenced a series of flanking attempts by one side and the other which
speedily resolved itself into the famous "race to the sea." This was a
competition between the opposing armies in rapid trench digging. The
effort on either side was made to prevent the enemy from executing a
flank movement. In an amazingly short time the opposing trenches
extended from the Belgian coast to the Swiss border, making further
outflanking attempts impossible of achievement.

[Illustration: Map: The North Sea and surrounding countries--Norway,
Denmark, Great Britain, France, Belgium, Holland, Germany.]
FORTS, FLYING AND NAVAL BASES ON THE NORTH SEA

This was not the first time in history that intrenched armies opposed
each other. The Civil War in this country set the fashion in that
respect. The contending sides in the Great War, however, improved vastly
upon the American example. Communicating trenches were constructed,
leading back to the company kitchens, and finally to the open road
leading back to the rest billets of the armies.

When night raiding commenced, it was speedily seen that straight
trenches exposed whole companies of men to enfilading fire. Thereupon
bastions were made and new defenses presented by zig-zagging the
front-line trenches and the communicating ditches as well.

To the formidable obstacles presented by the trenches, equipped as they
were with sand-bag parapets and firing steps, were added barbed-wire
entanglements and pitfalls of various sorts. The greatest improvement
was made by the Germans, and they added "pill boxes." These were really
miniature fortresses of concrete and armor plate with a dome-shaped
roof and loopholes for machine gunners. Only a direct hit by a
projectile from a big gun served to demolish a "pill box." The Allies
learned after many costly experiments that the best method to overcome
these obstacles was to pass over and beyond them, leaving them isolated
in Allied territory, where they were captured at the leisure of the
attackers.

Trench warfare brings with it new instruments. There are the flame
projectors, which throw fire to a distance of approximately a hundred
feet. The Germans were the first to use these, but they were excelled in
this respect by the inventive genius of the nations opposing them.

The use of poison gas, the word being used in its broad sense, is now
general. It was first used by the Germans, but as in the case of