not the numbers of men to be transported to the front, nor even
the astounding quantities of supplies required to feed those men,
which have been the primary cause for crisscrossing all Northern
France with this latticework of steel. It is the unappeasable appetite
of the guns. "This is a cannon war," Field-Marshal von Mackensen told
an interviewer. "The side that burns up the most ammunition is bound
to gain ground." And on that assumption the British are proceeding.
England's response to the insistent cry of "Shells, shells, shells!"
has been one of the wonders of the war. By January 1, 1917, the shell
increase for howitzers was twenty-seven times greater than in 1914-15;
in mid-caliber shells the increase was thirty-four times; and in all
the "heavies" ninety-four times. And the shell output keeps a-growing
and a-growing. Yet what avail the four thousand flaming forges which
have made all this possible, what avails the British sea-power which
has landed these amazing quantities of shells in France, and 2,000,000
of men along with them, if the shells cannot be delivered to the guns?
And that is where the great new systems of railway have come in.

"Be lavish with your ammunition," Napoleon urged upon his battery
commanders. "Fire incessantly." And it is that maxim which the
artillerists of all the nations at war are following to-day. The
expenditure of shells staggers the imagination. In a single day, near
Arras, the French let loose upon the German lines $1,625,000 worth of
projectiles, or almost as great a quantity as Germany used in the
entire war of 1870-71. Five million shells of all calibers were fired
by the British gunners during the first four weeks of the offensive on
the Somme. In one week's attack north of Verdun the Germans fired
2,400,000 field-gun shells and 600,000 larger ones. To transport this
mountain of potential destruction required 240 trains, each carrying
200 tons of projectiles.

During the "Big Push" on the Somme, there were frequently eighty guns
on a front of two hundred yards. The batteries would fire a round per
gun per minute for days on end, the gunners working in shifts, two
hours on and two hours off. So thickly did the shells fall upon the
German lines that the British observing officers were frequently
unable to spot their own bursts. A field-battery of eighteen-pounders
firing at this rate will blaze away anywhere from twelve to twenty
tons of ammunition a day. As guns firing wit