“What a time you’ve been,” she said. “Is all well? Have the Narwhals taken up their position?”

Satisfied on this point, she led the children up a way long and steep to a window in the wall whence they could look down on the ravine and see the advance of the foe. The Narwhals were halted about halfway up the ravine, where it widened to a sort of amphitheater. Here, among the rocks, they lay in ambush, waiting for the advance of the foe.

“If it hadn’t been for you, Reuben,” said the Princess, as they leaned their elbows on the broad rocky ledge of the window, “they might easily have stormed the North Tower—we should not have been ready—all our strongest defenses were massed on the south side. It was there they attacked last time, so the history books tell us.”

And now a heavy, thundering sound, faint yet terrible, announced the approach of the enemy—and far away across the sea plain something could be seen moving. A ball of seaweed seemed to drift up the ravine.

“A Sea Urchin gone to give the alarm,” said the Princess; “what splendid things Boy Scouts are. We didn’t have them in the last war. My dear father only invented them just before—” She paused and sighed. “Look,” she said.

The enemy’s heavy cavalry were moving in a solid mass toward Merland—the great Sea Horses, twenty feet long, and their great riders, who must have been eight or ten feet high, came more and more quickly, heading to the ravine. The riders were the most terrible beings the children had ever seen. Clothed from head to feet in closely fitting scales, with large heads, large ears, large mouths and blunt noses and large, blind-looking eyes, they sat each erect on his armored steed, the long harpoons swaying lightly in their enormous hands.

The Sea Horses quickened their pace—and a noise like a hoarse trumpet rang out.

“They are sounding the charge,” said the Princess; and as she spoke the Under Folk charged at the ravine, in a determined, furious onrush.

“Oh, no one can stand up against that—they can’t,” said Cathay, in despair.

From the window they could see right down onto the amphitheater, where the Narwhals were concealed.