In mid-1757 Austrian forces gradually pushed into Prussian-controlled Lusatia, while a combined French and "Reichsarmee" force under the Prince of Soubise approached the theatre from the west. On 7September the Austrians under Daun and Prince Charles, advancing into Upper Lusatia, defeated a Prussian force under Bevern and Hans Karl von Winterfeldt at the Battle of Moys, during which Winterfeldt was killed. Prince Charles's army then proceeded westward, hoping to link up with Soubise's force after the latter had traversed Saxony, while Bevern and his army retreated eastward to defend Lower Silesia.