The troops themselves had no fear,
no dread of the Trojans’ power and breakneck charges,
no, they stood their ground like heavy thunderheads
stacked up on the towering mountaintops by Cronus’ son,
stock-still in a windless calm when the raging North Wind
and his gusty ripping friends that had screamed down
to rout dark clouds have fallen dead asleep. So staunch
they stood the Trojan onslaught, never shrinking once.

– Homer

The Iliad, Book 5, lines 601-608. This epic simile tells us how the unshrinking Achaeans, spurred on to fight by their leaders, show no fear and hold their ground against the Trojans. They are likened to thunderheads stacked up on the mountaintops by the god of lightning Zeus.