The military term, field promotion describes a situation when a commanding officer is killed in action and a lower ranking individual automatically inherents their authority. In many jobs, a promotion is a great thing. Usually it comes with an increase in pay, more influence, and yes, more responsibilty.
But when you're promoted in the middle of combat, the situation gets more complicated. You're not put in charge of a group that voted you in, and you're not walking into a new job at a high level, you're taking authority of the group that just moments ago were your peers. The friends who used to complain about the Commander with you are now saluting you.
Earning the respect and wielding the proper authority to a group of employess that were just recently your equal can be difficult. Perhaps you're younger than some of them, less experienced, and you're meeting severe opposition to your leadership; that doesn't discount the fact that you were appointed to that position. Those in authority over you saw something in you to give you that authority; wield it confidently and have zero tolerance for backbiting.