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I
would just as soon have expected restraint from a hyena prowling amongst
the corpses of a battlefield.

Word:

Laughter.

Question:

Why does the speaker compare someone's lack of restraint to a hyena amongst battlefield corpses?

Answer (optional):

The speaker compares someone's lack of restraint to a hyena amongst battlefield corpses to emphasize the fact that the individuals in question had no earthly reason for any kind of scruple or restraint.