I have the comte de St. Germaine as one of the characters in one my timelines.
He was a distinguished French General in the 7 Years War (and others) who was appointed commanding General of the Danish Army after the 7 war and was in charge of defending against the Russians.
Denmark had a competent army. They stayed out of the 7 Years War as they didnt' have a dog in the fight and made profits from both parties.
Denmark got subsidies from both sides at various points to stay out. They were big winners in that war.
Per wikipedia, "They also avoided involving Denmark in the
European wars of his time. The country remained neutral even for the duration of the
Seven Years' War (1756–63), despite its proximity to combatants
Russia and
Sweden, an act which undoubtedly shaped the perception of the period as a happy time."
in 1763, Denmark was outnumbered but the Russian Army was far from home and had long lines of communication. I can't believe Russia would have any allies to help.
Possibly Austria might step in to keep a foreign power from mucking about the Holy Roman Empire.
It would have been an interesting fight.
King Frederick was dissolute and left everything to his minister, Moltke.
His last words were, "It is a great consolation to me in my last hour that I have never wilfully offended anyone, and that there is not a drop of blood on my hands