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]
(..) We go back a while. We went to the Academy together. We were commissioned together. We did our tours in Vietnam together. But I've been promoted up through the chain... with greater speed and success than you have. Now, if that's a source of tension... or embarrassment for you... (..)1992 A Few Good Men
(..) And now he's telling tales about a fence line shooting. Matthew? I'm appalled, sir. You're appalled. This kid broke the chain of command and ratted on a member of his unit... to say nothing of the fact that he is a U.S. Marine... and it would appear he can't run from here to there... (..)1992 A Few Good Men