THE WORLD TO-DAY	425
the field against the Central Powers (Germany and Austria),
and the German attempt to enter France through Belgium
(violating the treaty guaranteeing Belgian neutrality as a
mere * scrap of paper') brought Great Britain and her Em-
pire into the fray. Bulgaria and Turkey were soon en-
tangled with Germany and Austria, while Italy, Greece, and
the Arabs joined the Allies (England and France) one after
another. But the most decisive factor which tilted the balance
and fortunes of war against the Germans and their allies
was the entry of the United States of America in 1917. In
the Far East, Japan threw in her weight on the side of
England as a result of the Anglo-Japanese alliance formed
in 1902.
Though in the course of human history longer wars (like
the Hundred Years' War) had been fought, this Great War
was unparalleled in its disastrous consequences. Not merely
was it the first war in which the whole World was directly
or indirectly involved, but it was also unique in its concen-
tration of energies for the destruction of men and materials.
It was the first war in human history to be fought in three
dimensions, on account of the addition of the aerial arm
and the submarine Science revealed for the first time its
baleful potentialities. During those four years of arma-
geddon Humanity appeared to strain every nerve to see
through the struggle once and for all. The following sketch
of one of its trying moments might convey to the reader a
faint glimpse of its grim character :
" In the low-lying plain of Flanders, where the British held
Ypres salient against many German attempts to drive through
to the channel ports, the warfare was partly amphibious since
the trenches filled with water in the wet winter weather. At
times, by day, there was hardly a sign of life above the ground,
behind the barbed wire which protected the two lines of hostile
trenches, with a No Man's Land of varying width between. Even