threatened
them.

"Rob, tell us what it was all about?" Tubby managed to gasp, when,
having reached the road again, they were hurrying back as rapidly as
they could go, the horses helping to drag them along.

"Just this," Rob told him briefly. "They've fixed a mine there under the
bridge, so as to blow it up; and we've had the narrowest escape of our
lives!"

CHAPTER VI.

GETTING NEAR THE WAR ZONE.

"Hold on to your horses, everybody!" called out Merritt, as he looked
back toward the bridge from which they had now managed to press quite a
little distance.

Merritt somehow did not seem to be very much astonished at what Rob had
said. It might be he himself had entertained suspicions along those same
lines.

They had heard that the determined Belgians were engaged in throwing all
the obstacles possible in the way of an advance in force on the part of
the invaders. If only cavalry were to be dealt with, the defenders of
the soil had faith in their ability to take care of all that could be
sent against them; but it was known to be a fact that the artillery arm
was what the Germans meant to depend on more than anything else in this
war for conquest.

If bridges and culverts were destroyed in every direction before the
enemy could take possession of the roads, it would be next to impossible
to move the great siege guns until some sort of strong temporary
structure had been built in place of the stone and steel fabrics that
were blown up.

And so, for days, there had been reports drifting in to Antwerp that
certain bridges had been marked for destruction. Those who sallied forth
in armored cars to speed over the country, and play havoc with their
Maxim guns, found it necessary to revise their map of the district every
night so as to conform to the new changes that had been wrought.

It was hardly ten seconds after Merritt told them to keep a firm grip on
the bridles of their horses that the boys on looking back saw the bridge
suddenly rear itself in the air. Then came a terrifying boom that made
the very ground under their feet quiver; and, in a moment later, in
place of the fine bridge lay a horrible gap, from which smoke and dust
was arising in sickening clouds.

Tubby was as white as a sheet. The others could hear the big sigh with
which he drew in a gulp of air.

"I want to say right here," he started to remark solemnly, "that I'm
thankful I've got such a cracking good nose for queer odors. Think w