Simplify the following text for a Grade 13 native English-speaking person.
Original: In 1631 , during the Thirty Years ' War , the emissaries of George William , Elector of Brandenburg met at KÃ penick - then some distance outside Berlin - with the approaching army of Gustav Adolph , King of Sweden , in a vain effort to stop the ongoing devastation of Brandenburg .
Simplified: In 1631 , during the Thirty Years ' War , the emissaries of George William , Elector of Brandenburg went to KÃ penick to meet the approaching army of Gustav Adolph , King of Sweden , to try to stop the devastation of Brandenburg .