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]
(..) I'll be goddamned if I'm gonna watch Hayes pull flowers out of his ass... and take credit for this one. I'll be sure to pass your request along to my chain of command. Good. Now, how's my girl doin', anyway? You need to know what it feels like to drown... (..)1997 G.I. Jane