I know this is well known but just wanted to point out Brennus and his boss move (according to Livy) after sacking Rome in 390:

“At last the Gauls consented to accept a ransom of a thousand pounds of gold. As it was being weighed out, the Roman tribune complained of some unfairness. Brennus at once threw his heavy sword into the scale; and when asked the meaning of the act, replied that it meant Vae victis (" woe to the conquered").”