Both lads spoke French and German fluently and each had a smattering of
Italian. Also, as the result of several trips to Russia, they had a few
words of the Russian tongue at their command.

In physical strength, Jack excelled Frank by far, although the latter was
by no means a weakling. On the other hand again, Frank was a crack shot
with either rifle or revolver; in fact, he was such an excellent marksman
as to cause his chum no little degree of envy. Then, too, both lads were
proficient in the art of self defense and both had learned to hold their
own with the sword.

Up to the time this story opens the combined allied fleets had succeeded
in keeping the Germans bottled up in the strong fortress of Helgoland.
True, the enemy several times had sallied forth in few numbers, apparently
seeking to run the blockade in an effort to prey upon allied merchant
ships. But every time they had offered battle they had received the worst
of it. They had been staggered with a terrible defeat at Jutland almost a
year before this story opens, and since that time had not ventured forth.

But even now, in the security of their hiding places, the Germans were
meditating a bold stroke. Submarines were being coaled and victualed in
preparation for a dash across the Atlantic. Already, one enemy
submarine--a merchantman--had passed the allied ships blocking the English
channel and had crossed to America and returned. Some months later, a
U-Boat of the war type had followed suit. A cordon of ally ships had been
thrown around American ports to snare this venturesome submarine on its
return, but it had eluded them and returned safely to its home port.

But soon--very soon, indeed--German undersea craft were to strike a more
severe blow at allied shipping, carrying, for the moment, the war in all