Miracle of the House of Brandenburg
The Miracle of the House of Brandenburg is the name given by Frederick II of Prussia to the failure of Russia and Austria to follow up their victory over him at the Battle of Kunersdorf on 12 August 1759 during the Seven Years' War. On 6 January 1762, Frederick the Great wrote to Count Karl-Wilhelm Finck von Finckenstein, "We ought now to think of preserving for my nephew, by way of negotiation, whatever fragments of my territory we can save from the avidity of my enemies." A fortnight later, he wrote to Prince Ferdinand of Brunswick, "The sky begins to clear.
Source: Wikipedia — Miracle of the House of Brandenburg (CC BY-SA 4.0)