Onslaught (noun)

1. A fierce or destructive attack or invasion.
2. A large number of similar things arriving or happening at the same time.

Origin:

Late middle english (in the sense "an attacking"): from old french onsalte, from onsalter "to assault", from on "on" + salte "leap, rush".

Examples:

1. The city was under attack from an onslaught of enemy soldiers.
2. An onslaught of emails flooded my inbox.
3. The company was not prepared for the onslaught of customers during the holiday season.
4. The new regulations have been met with an onslaught of criticism from the industry.
5. The stock market took a hit during the economic onslaught of the Great Depression.