But there's a difference. Earth's government knew Earth was being
threatened, and they knew they had to get as many facts as they could.
They were also aware of the fact that if you know a thing _can_ be done,
then you will eventually find a way to do it.

During the next fifty years, Earth learned more than it had during the
previous hundred. The race expanded, secretly, moving out to other
planets in that sector of the galaxy. And they worked to catch up with
the Rats.

They didn't make it, of course. When, after fifty years of presumably
peaceful--but highly limited--contact, the Rats hit Earth, they found
out one thing. That the mass and energy of a planet armed with the
proper weapons can not be out-classed by any conceivable concentration
of spaceships.

Throwing rocks at an army armed with machine guns may seem futile, but
if you hit them with an avalanche, they'll go under. The Rats lost
three-quarters of their fleet to planet-based guns and had to go home to
bandage their wounds.

The only trouble was that Earth couldn't counterattack. Their ships were
still out-classed by those of the Rats. And the Rats, their racial pride
badly stung, were determined to wipe out Man, to erase the stain on
their honor wherever Man could be found. Somehow, some way, they must
destroy Earth.

And now, Al Pendray thought bitterly, they would do it.

* * * * *

The _Shane_ had sneaked in past Rat patrols to pick up a spy on one of
the outlying Rat planets, a man who'd spent five years playing the part
of a Rat slave, trying to get information on their activities there. And
he had had one vital bit of knowledge. He'd found it and held on to it
for over three years, until the time came for the rendezvous.

The rendezvous had almost come too late. The Rats had developed a device
that could make a star temporarily unstable, and they were ready to use
it on Sol.

The _Shane_ had managed to get off-planet with the spy, but they'd been
spotted in spite of the detector nullifiers that Earth had developed.
They'd been jumped by Rat cruisers and blasted by the superior Rat
weapons. The lifeboats had been picked out of space, one by one, as the
crew tried to get away.

In a way, Alfred Pendray was lucky. He'd been in the sick bay with a
sprained ankle when the Rats hit, sitting in the X-ray room. The shot
that had knocked out the port engine had knocked him unconscious, but
the shielded walls of t