The planned Russian invasion of Holstein by Peter III. Say Prussia is defeated and dismembered earlier than OTL, Russians celebrate a victory, get parts of PLC for Prussia and then Elisabeth dies and Peter inherits. What was the state of the Danish army at the time? Was their navy strong like in the 17th century? Possible Russian gains, if and how they win? And would the foreign powers take part? Sweden wasn't really strong at the time and worn out by the war so they probably couldn't take Norway alone. But their and Russian navy combined could take on the Danes, right?
So, thoughts, comments etc.