La Sibylle submerged, and surface ships of the French Mediterranean Squadron followed her course on Asdic detectors for an hour.

He would turn on his ASDIC, and all fish within range would echo back, "Here we are."

ASDIC, designed for submarine hunting, sends ultrashort sound waves through the water and any sizable object reflects them.

There are the harsh sounds of war: shells bursting on deck armor, the asdic set clicking and pinging with echo bearings, the shattering explosions of ammunition ships, the groaning, slamming violence of a small ship fighting a monstrous sea.

But the whales, nimbler than U-boats, dove out of Asdic's sonic beam, and the gunners had to rely, as of old, on their knowledge of whale psychology.