onslaught

noun
  1. A fierce or destructive attack. noun
    The army launched an onslaught against the enemy forces at dawn.
    The city was unprepared for the onslaught of the hurricane.
  2. An overwhelmingly large number of people or things, often arriving suddenly. noun
    The store was unprepared for the onslaught of customers during the holiday sale.
    The website crashed due to the onslaught of traffic after the announcement.