He turned to history for inspiration. Frederick did not have the resources of his enemies. His army was not as big as either France or Russia. Prussia was actually a small country with a small population. So he needed to have the best tactics and strategies. Many of his ideas that he used in his battles came from history.
Frederick studied the histories to develop new strategies for his battles. He studied the battles of Alexander the Great, Cyrus the Great and other ancient kings and generals. Frederick used the tactics that he discovered in history to win battles against much larger armies at Sohr, Rossbach, Leuthen and Liegntitz . Based upon his readings he developed his famous ‘Schwehrpunkt’ manoeuvre.