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]
(..) -Thirty-two. But l'll tell you. it took every bit ot strength l had... ...to hold it while the guy took the picture. Every damn bit. Probably that chain didn't help it any. either. You didn't weigh the chain. did you? No. l didn't weigh the chain. But l'm awfully proud ot that picture. (..)1975 One Flew Over the Cuckoo's Nest