"Then why do we not fly over and land an army and great guns and batter
down the walls of Berlin and he done with it?"

"That, as you know if you studied your history, has been tried many
times and always with disaster. The bomb-torn soil of that black land is
speckled white with the bones of World armies who were sent on landing
invasions before you or I was born. But it was only heroic folly, one
gun popping out of a tunnel mouth can slay a thousand men. To pursue the
gunners into their catacombs meant to be gassed; and sometimes our
forces were left to land in peace and set up their batteries to fire
against Berlin, but the Germans would place Ray generators in the ground
beneath them and slay our forces in an hour, as the Angel of Jehovah
withered the hosts of the Assyrians."

"But why," I persisted, "do we not tunnel under the Ray generators and
dig our way to Berlin and blow it up?"

My uncle smiled indulgently. "And that has been tried too, but they can
hear our borings with microphones and cut us off, just as we cut them
off when they try to tunnel out and place new generators. It is too
slow, too difficult, either way; the line has wavered a little with the
years but to no practical avail; the war in our day has become merely a
watching game, we to keep the Germans from coming out, they to keep us
from penetrating within gunshot of Berlin; but to gain a mile of
worthless territory either way means too great a human waste to be worth
the price. Things must go on as they are till the Germans tire of their
sunless imprisonment or till they exhaust some essential element in
their soil. But wars such as you read of in your history, will never
happen again. The Germans cannot fight the world in the air, nor in the
sea, nor on the surface of the earth; and we cannot fight the Germans in