Please answer the following question: Given the following passage  "The year 1759 saw several Prussian defeats. At the Battle of Kay, or Paltzig, the Russian Count Saltykov with 47,000 Russians defeated 26,000 Prussians commanded by General Carl Heinrich von Wedel. Though the Hanoverians defeated an army of 60,000 French at Minden, Austrian general Daun forced the surrender of an entire Prussian corps of 13,000 in the Battle of Maxen. Frederick himself lost half his army in the Battle of Kunersdorf (now Kunowice Poland), the worst defeat in his military career and one that drove him to the brink of abdication and thoughts of suicide. The disaster resulted partly from his misjudgment of the Russians, who had already demonstrated their strength at Zorndorf and at Gross-Jägersdorf (now Motornoye, Russia), and partly from good cooperation between the Russian and Austrian forces.",  answer the following question. Note that the answer is present within the text.  Question: What caused the defeat that occurred in Kunowice, Poland?
Answer:
misjudgment of the Russians