one dog barks at a shadow and the pack barks at the noise—chime in (/echo/parrot/follow others) blindly;one barking dog sets all the street a-barking;slavishly echo others
❍ 突然，一位官员对他发动了人身攻击，一伙无耻文人，～，跟着叫嚣起来。Suddenly an official launched personal attacks on him with a batch of shameless scholars raving all at once.It was just like one dog barking at a shadow and the pack joining it.
吠形吠声形（影）fèi xínɡ fèi shēnɡ
吠：狗叫。一只狗看见人就叫，很多狗听到了叫声也跟着叫。比喻随声附和，没有主见。slavishly echo others, chime in blindly, echo blindly, blindly follow others