In December 1674, Louis XIV of France called upon Sweden to invade Brandenburg. Wrangel advanced into the Uckermark, a region on the Brandenburg-Pomeranian frontier, securing quarters for his forces until the weather would permit him to turn westwards to Hanover. Frederick William I, Elector of Brandenburg received the news in the Rhine valley, and turned northeast to confront Wrangel. On 18 June (OS) or 28 June (NS) the armies met in the Battle of Fehrbellin