They were 'cowed' into silence by threats. [=they did not complain, publicly say anything, etc., because they had been threatened]
They'll be arguing about this 'till the cows come home'.
The football team was a 'cash cow' for the university.
(..) Your jailer, huh? Yeah, boy, I'm makin' such a great deal on you, You wouldn't believe it. You're a regular cash cow, kid. That plus $ million, I could probably retire by the time I'm years old. Look, you're gonna have to help me out a little bit here. (..)1993 Free Willy