“They’re an irresponsible lot, anyhow,” said Bob. “Besides, we’ve got General Pitou below, and General Mendez will have an easy time of it when he gets here with his army. The uprising is as good as squelched. If anything——”

A perfect roar of guns echoed from the hill. With a crash the periscope mast went by the board, and the round shot caused the water to bubble and boil all around the submarine.

“They’ve got a grouch against that periscope, you see!” laughed Dick.

“We’ll have to have a new mast and ball as soon as we get back to Belize,” said Bob, as he guided the Grampus in a wide sweep around the headland to the left of the river mouth.

“A moment more,” said Dick, “and we’ll have the town between us and the fort. They’re slow at loading those old carronades. Those fellows’ hands must be all thumbs. If——”

Dick did not finish his sarcastic remarks. Just then there was a tremendous explosion just behind the submarine. A column of water arose high in the air, and, descending in a huge wave, carried the stern of the boat under and threw the bow high in the air. The water all around was a veritable caldron.

Frantic cries came from within the hull. Bob, owing to the almost vertical inclination of the steel hull, was hurled out of the conning tower and came into violent collision with Dick, who was clinging with a life-and-death grip to the flagstaff guys.

For a second the Grampus heaved and tossed on the waves, then righted herself and drove ahead.

Bob picked himself up and climbed hastily back into the conning tower. He was sore and bruised, but he realized that he could not leave the submarine to steer herself.

“What was that?” cried Dick, rising to his knees and lifting a pale face upward.