Tight formations led by Hector careering breakneck on
like a deadly rolling boulder torn from a rock face –
a river swollen with snow has wrenched it from its socket,
immense floods breaking the bank’s grip, and the reckless boulder
bounding high, flying with timber rumbling under it,
nothing can stop it now, hurtling on undaunted
down, down till it hits the level plain
and then it rolls no more for all its wild rush.
So Hector threatened at first to rampage through
the Argives’ ships and shelters and reach the sea
with a single sudden charge, killing all the way.

– Homer

The Iliad, Book 13, lines 163-173. Hector and his Trojans advance to the Achaean ships in this passage, killing all before them. An extended Homeric simile compares the charge to an unstoppable deadly boulder ripped from a rock face by a swollen river and hurtling down to the plain.