Protesters formed 'a human chain' [=they stood next to each other with their arms linked] around the ancient tree to prevent it from being cut down.
In the United States, the President as the commander in chief is at the head of the military 'chain of command'.
I thought he really won the lottery but he was only 'pulling my chain'. [=he was only playing a joke on me]
(..) You understand? Please, Glen, please. I'm askin' for your help. He's gonna die. There's a -foot length of chain And a winch control Behind the seat of the truck. Go and get it. Thanks, Glen. (..)1993 Free Willy