between whom did it happen?
Between Prussia and Austria
Third Silesian War
 between Prussia and Austria 
when did the third silesian war take place? 1756 to 1763
wiki:6305689
Third Silesian War [SEP] Introduction
The Third Silesian War () was a war between Prussia and Austria (together with its allies) that lasted from 1756 to 1763 and confirmed Prussia's control of the region of Silesia (now in south-western Poland). The war was fought mainly in Silesia, Bohemia and Upper Saxony and formed one theatre of the Seven Years' War. It was the last of three Silesian Wars fought between Frederick the Great's Prussia and Maria Theresa's Austria in the mid-18th century, all three of which ended in Prussian control of Silesia. This conflict can be viewed as a continuation of the First and Second Silesian Wars of the previous decade.