Both Jack and Frank had risen swiftly in the British service.  They had seen active service in all quarters of the globe and had fought under many flags.

Under Lord Hastings’ command they had been with the British fleet in the North Sea when it struck the first decisive blow against the Germans just off Helgoland.  Later they were found under the Tricolor of France and with the Italians in the Adriatic.  With the British fleet again when it sallied forth to clear the seven seas of enemy vessels, they had traversed the Atlantic, the Pacific and the Indian oceans.  It had been their fortune, too, to see considerable land fighting.  They had been with the Anglo-Japanese forces in the east and had conducted raiding parties in some of the German colonial possessions.

Several times they had successfully run the blockade in the Kiel canal, passing through the narrow straits in submarines just out of reach of the foe.  In Russia, they had, early in the war, lent invaluable assistance to the Czar; and more lately, they had been in the eastern monarchy when Czar Nicholas had been forced to renounce his throne.

Once since the war began they had been to America.  This was shortly after the United States entered the war.  They were ordered to the North Atlantic in order to help the American authorities snare a German commerce raider which, in some unaccountable manner, had run the British blockade in the North sea, and was wreaking havoc with allied shipping.  Later they went to New York, and then returned to Europe with a combined British-American convoy for the first expeditionary force to cross the seas.

In temperament and disposition Jack and Frank were as unlike as one could conceive.  Jack, big for his age, broad-shouldered and strong, was always cool and collected.  Frank, on the other hand, was of a more fiery nature, easily angered and often rash and reckless.  Jack’s steadying influence had often kept the two out of trouble, or brought them through safely when they were in difficulties.

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.