 After marching 250 kilometres in 15 days back to Brandenburg, he caught the Swedes by surprise and managed to defeat them on the field at the Battle of Fehrbellin, destroying the myth of Swedish military invincibility.He later destroyed another Swedish army that invaded the Duchy of Prussia during the Great Sleigh Drive in 1678.He is noted for his use of broad directives and delegation of decision-making to his commanders, which would later become the basis for the German doctrine of Auftragstaktik, and for using rapid mobility to defeat his foes.