"Later Frederick the Great swore never again to leave his troops behind in battle and adhered to this promise faithfully until his death in the late 18th century."
Not true! Frederick would later leave the battlefield of Lobositz (October 1, 1756) early, again to have his infantry win the battle for him. And in 1757, he left the field of Kolin (June 18) early, as he suffered his first defeat at the hands of the Austrian Marshal Daun.