All 3 Uses of

onslaught
in
The Iliad by Homer - (translated by: Butler)

He rushed across the plain like a winter torrent that has burst its barrier in full flood; no dykes, no walls of fruitful vineyards can embank it when it is swollen with rain from heaven, but in a moment it comes tearing onward, and lays many a field waste that many a strong man's hand has reclaimed—even so were the dense phalanxes of the Trojans driven in rout by the son of Tydeus, and many though they were, they dared not abide his onslaught.†
Book 5

onslaught = powerful attack; or sudden and enormous amount of something that must be handled

When they were beyond the trench that was dug round the wall they held their meeting on the open ground where there was a space clear of corpses, for it was here that when night fell Hector had turned back from his onslaught on the Argives.†
Book 10 *

The Argives on their part raised a shout likewise, nor did they forget their prowess, but stood firm against the onslaught of the Trojan chieftains, and the cry from both the hosts rose up to heaven and to the brightness of Jove's presence.†
Book 13

Definition:

a powerful attack

or:

a sudden and enormous amount of something that must be handled -- such as trouble, people or communications