Conversation so far:
Did Claudius assassinate Caligula?
There is no evidence that Claudius had a direct hand in the assassination.
How was Claudius involved?
although it has been argued that he knew about the plot -- particularly since he left the scene of the crime shortly before his nephew was murdered.
What happened after the murder?
Claudius witnessed the German guard cut down several uninvolved noblemen, including many of his friends.
Did Claudius do anything to stop the German guard?
He fled to the palace to hide.
What happened after he hid?
a Praetorian named Gratus found him hiding behind a curtain and suddenly declared him princeps.
Did he rule Rome?
CANNOTANSWER.

Question: What happened after Gratus found him?
Self-contained rewrite: What happened after Gratus found Claudis?