"Stand-by depth charge attack!"
Termagant's men had seen action before. They knew how her quarterdeck could spew out the crushing canisters of high-explosive amatol, and they felt a rising certainty that this particular Japanese submarine was due shortly for a violent and conclusive death.
The order from the bridge was all they needed to relax their vigilance a little and to savour in its place the grim and pleasurable certainty that the ship was about to kill.
So that none of them was prepared for the next startling evidence of the progress of the hunt.