"Well," said Jack, "I hope we see some action soon, whether it is at Duala, as you call it, or some other place. This is growing monotonous." Frank's prophecy proved correct. Even now the Cumberland and the Dwarf were well into the Gulf of Guinea and making all headway toward the mouth of the river Cameroon, which point the vessels reached early the following morning, intending to anchor in the mouth of the stream. At the approach of the cruisers, however, a fort guarding the harbor broke into action. A few well-directed shots from the big guns of the Cumberland, and the fort was silenced. Then, instead of coming to anchor, the cruisers steamed slowly up the river. Rounding a bend in the stream, Duala could be seen in the distance; likewise the forts guarding the town, and a bombardment of the fortifications was at once begun. The shore batteries promptly returned the fire, but it soon became apparent that the guns on the ships outranged them. For several hours the bombardment continued, and then two merchant steamers were seen making their way from the shelter of the port directly toward the British ships. "Wonder what's up now?" said Frank, who at that moment, having been relieved from duty, stood beside Jack at the rail. "Don't know," was the latter's brief reply. Nor did anyone else, so those on board the cruisers watched the movements of the oncoming steamers with much curiosity. When the approaching vessels were little more than a mile up the river they came to a stop. Small boats were lowered over the sides and put off hurriedly in the direction from which they had come. Shortly after, a blinding glare rose to the sky, there was the sound of two terrific reports, one immediately following the other, and the two steamers slowly settled into the water. Captain Marcus, on the bridge of the Cumberland, cried out: "They have blockaded the river!" It was true. The ruse was plainly apparent now that it was too late to prevent it. The two sunken vessels made further progress up the river by the British ships impossible. "Wonder what we shall do now?" asked Frank. "Haven't any idea," said Jack briefly. Night drew on and still the British guns continued to hurl their shells upon the German town. With the fall of darkness there came an answer to Frank's question. Captain Marcus summoned Frank and Jack. "The Germans have effectually blocked the river," he told them. "Therefore we cannot capture the town that way. Because of your experience, I have called you two lads to undertake a most dangerous mission.