Use 'whereupon' to indicate the next event in a sequence of actions. She rang the bell, whereupon the gates swung open.
Pro Tip 2/3
Literary Use
'Whereupon' can sound formal or old-fashioned, often used in literature or formal narratives. The jury delivered the verdict, whereupon the judge passed sentence.
Pro Tip 3/3
Immediate Response
'Whereupon' suggests an immediate reaction or consequence to an action. The lights went out, whereupon everyone screamed.