being. Moreover, they were puzzled. Why should the Allied "schwein"
fly so low, yet do no harm where once they had wrecked things only a
few days before? What were they up to, anyhow?

This query was not answered at once. The telephones roused the Huns in
the front trenches. Yet it puzzled them, too. Hitherto the bombing on
both sides had been done mostly from far above. Such skimming the
ground across No-Man's-Land might mean anything.

Presently the thrum of approaching planes became more and more audible
along that portion of the front.

From his plane Blaine made private signal to the others to put on all
speed. Erwin did likewise. Consequently it was not a minute before
the raiders were upon the front trenches, going at the rate of two
miles a minute. Each man in those planes sat with an open nest of hand
grenades within easy reach. The handle of the gun crank was handy,
its deadly muzzle pointed along the top of the fuselage of each mobile
plane.

Then a pistol shot rang out, and at the signal grenades were dropped as
the now far extended line passed over those open trenches in which
troops were massed. For, be it known, that fatal blue flare from the
aerodrome a dozen or more miles away had filled those trenches yet more
full of human cannon fodder. Hence the bombing was all the more deadly.

Passing the trenches, at another signal, the hostile planes nimbly
wheeled, shot back again and poured forth more bombs upon those
trenches. Still again they wheeled and traversed them for the third
time.