descend upon

Short definition from Wiktionary

Verb

1. 1
   To arrive, usually without warning or invitation: To make an attack or incursion, from or as if from a vantage ground; to come suddenly and with violence.
2. 2
   To arrive, usually without warning or invitation: To arrive suddenly or unexpectedly, especially in a manner that causes disruption or inconvenience.
3. 3
   To visit in large numbers, especially a public place.